Hi MohitK,
The command line is correct. I have deployed the same software successfuly in my environment. The error that the agent returns you I have experienced a lot as well. Not only related to .NET deployments.
What I figured when these kind of errors were returned by the agent is that the package in the "cache" folder of the Software Delivery (Program Files\Altiris\Altiris Agent\Agents\SoftwareManagement\Software Delivery) were not similar to the one located on the site server, so I had to delete that folder and send the task again, so that the agent could download the package from zero once more. But there are other scenarios, such as the package on the site server not being downloaded successfully from the Altiris server, resulting in a corrupted package. Once the agent responding to that site server downloaded the package from it, the task failed because of the package on the site server.
You mentioned you tried to run your package manually and it worked, but did you run the package located in the "cache" folder? If not, first of all you need to make sure your package is not corrupted on the Altiris server, and then verify it if that did not happen on the site server as well.