If Inventory Solution data classes are not populated, the Inventory to Asset Synchronization task will not be able to work; there is nothing to synchronize to CMDB. Verify that the Inventory Solution data exists. Instructions will vary depending on what versions are used. Note: Inventory to Asset Sync does not merge records, which is a common misconception of how this task works. This task only copies data from Inventory data classes to CMDB data classes. The following article describes how this works in more detail:

Under what conditions will the Inventory to Asset Synchronization task update the Asset data classes?
http://www.symantec.com/business/support/index?page=content&id=HOWTO7202

1. Find a computer that should have populated Inventory Solution data classes. In the Altiris console, go to View > Resources, and then on Resources > Configuration Items > Asset Types > IT > Computer.
2. Find a computer from the list and right click on it and choose Resource Manager > Summaries tab. 
3. Look at the Internal serial number, Computer manufacturer, and Model fields. These are populated by Inventory Solution, not Asset Management Solution.
4. If these fields are not populated, then the Inventory to Asset Synchronization task will not be able to work. First correct what ever Inventory Solution hardware reporting issue exists before next running the Inventory to Asset Synchronization task. Check the following Inventory Solution areas:
   
   
   1. This could be caused by the client not having the Inventory Agent Package installed from a Hardware Inventory task. Ensure that the computer is part of the collection that is specified on the Hardware Inventory task. On a client, right click on the Altiris Agent in the Windows system tray and click on Agent Details. The Inventory Agent Package should appear in the Installed Agents box. If not, it does not have one installed.
   2. This could be caused by the client not reporting in. Check the Computers Not Reporting Inventory in Last 'N' Days Inventory Solution report, found in View > Solutions > Inventory Solution, and then in the Reports > Windows > Inventory Agent > Inventory Capture folder.
   3. This could be caused by the Inventory Agent Package on the client failing to run. On a client, right click on the Altiris Agent in the Windows system tray and click on Altiris Agent. Under Options, click to enable Show internal tasks and packages. This should show the Inventory Agent Package. Double click on it to view run history. You may see errors here, indicating that the agent has not been able to run the hardware inventory or check in correctly.
   4. This could be caused by the schedule of the Hardware Inventory task not running often. On the task, check the Run on a schedule date and time. By default, this is 2:00 AM Daily. If this is set to a less frequent schedule, consider changing this so that hardware inventory is reported in sooner.
   5. This could be caused if there are duplicate resources, serial numbers, or GUIDs present, which can be caused by using the same image of a computer over and over on multiple computers (not recommended), causing duplicates to appear in the database. Check to see if there are the same computer names, serial numbers, and GUIDs in the Computer list from Step 1. Also, in SQL, use the following query to check for duplicates:
      
      USE Symantec_CMDB
      SELECT *
      FROM vComputer
      WHERE Guid = '<guid>'
      
      Where "<guid>" is the computer GUID to search for. Copy the GUID of the computer that you want to search for and then paste it as the <guid> in the query. This will return any computer that has the same GUID. The same process can be used for the computer name or serial number by changing the "where" condition and its value to search for.
      
      For more information on duplicate GUIDs, please refer to the following Notification Server article:
      
      Shared Guid Diagnostics Guide (aka Duplicate Guid Kit)
      http://www.symantec.com/business/support/index?page=content&id=HOWTO8090
      
      For imaging or re-using hard drives, make sure that the Altiris Agent GUID has been reset first (before taking the image for example). This will help prevent duplicates from occurring. If this has already occurred, it could be difficult to correct the symptoms in CMDB. To reset the Agent GUID, please refer to the following article:
      
      Altiris Agent Utility Tool
      http://www.symantec.com/business/support/index?page=content&id=HOWTO5511
      
      There are also various merge tasks that can be performed to combine duplicates. These are located by clicking on View > Tasks, and then on Assets and Inventory > Merge Assets (reports), and also in View > Configuration, and then in Solution Settings > CMDB Solution > Merge Resources (custom CMDB merge rules). Duplicates can also be merged by right clicking on multiple assets, and then on Merge Resources, when in View > Resources, and then on Resources > Configuration Items > Asset Types > IT > Computer. Note: The Duplicate Computer Merge found under CMDB Solution > Merge Resources is only intended to be used with unmanaged (Asset) to managed (Inventory) computers. To merge all types, use a custom  CMDB merge rule instead.
      
       
   6. For more assistance, please contact the Inventory Solution Technical Support team.
      
       
5. If these fields are populated, however, then this indicates other issues:
    
   1. This could be caused by the Inventory to Asset Synchronization never having been run (it is not enabled by default) or not scheduled to run. Use the Run Now button or enable a schedule, then click the Apply button.
   2. This could be caused if the collection for the Inventory to Asset Synchronization task does not contain the computers in question. Ensure that these are part of the Include these resources collection on this task.
   3. Certain conditions need to be met before the sync can work. These are described in the following article:
      
      Under what conditions will the Inventory to Asset Synchronization task update the Asset data classes?
      http://www.symantec.com/business/support/index?page=content&id=HOWTO7202
       
   4. For additional information on this sync, please refer to the following article:
      
      How can I update CMDB data to match Inventory data after hardware has been replaced?
      http://www.symantec.com/business/support/index?page=content&id=HOWTO8924
       
   5. Data replication may be occurring. If Standalone Replication Rules are present (or for 6.0, Inventory Forwarding), this may be overwriting the fields with the forwarding server's data for them. Disable this aspect to resolve this.
   6. For more assistance, please contact the Asset Management Solution Technical Support team.
       

Related Article

CMDB task "Inventory to Asset Synchronization" does not sync the System Number
http://www.symantec.com/business/support/index?page=content&id=TECH186918