The problem is that your posting contains insufficient information.

You are calling the Execute program from destination custom action from where?  UIsequence? ExecuteSequence?  Is 7-zip installed by an MSI?  (Uninstall.exe may be a wrapper file which starts an MSI uninstall).

Have you identified the correct command line arguments for Uninstall.exe to ensure a silent install without any dialogs? (Is this even possible?)

>before that the execution will continue without uninstalling the 7zip. 

This is unclear - are you saying that your MSI install continues without waiting for the uninstall to complete?

If that is the case, then you need to make your action Synchronous rather than Asynchronous.

The 64-bit of 7-zip has an MSI 32-bit an EXE setup.

Use the "/S" switch for silent uninstall.

Thanks for the information

I am calling the Execute program from destination custom action in  UIsequence.  7zip is already installed by MSI. While uninstalling MSI i want to uninstall 7zip.

 MSI Uninstall continues without waiting for the uninstall of 7Zip to complete.

I tried with custom action Execute Program from Destination in UI Sequence

C:\Program Files\7-Zip\Uninstall.exe

 action is Synchronous, igonre exit code.  The MSI Uninstall continues without waiting for the uninstall of 7Zip to complete.

Then i tried with  action C:\Program Files\7-Zip\Uninstall.exe /S    its working fine.

I tried to Uninstall Apache Tomcat 4.1 using the same custom action Execute program from destination custom action in  UIsequence.

"C:\Program Files\Apache Group\Tomcat 4.1\uninst-tomcat4.exe" /S

tomcat is not uninstalling MSI Uninstall continues without waiting for the uninstall of Tomcat  to complete.

what is the probelm?

Have you tried manually uninstalling Tomcat from the command line using the string you quoted? 

You have also stated that Tomcat is not uninstalling, while at the same time, you have stated that the MSI Uninstall continues without waiting for the uninstall of Tomcat, which implies that it IS uninstalling. So which is it?

Tomcat may require different command line switches for a silent uninstall, or a silent uninstall may not be possible. If it is possible, then the uninstall may open a parent window, which spawns a child window. If the parent window then closes, the uninstall is considered complete, regardless of whether the child window is still running. This is not uncommon, and if that is the case with Tomcat, then you would need to create an uninstall "wrapper" to handle the Tomcat removal which monitors the processes and terminates when all Tomcat processes are finished.