Deployment problems of Endpoint protection from EA server

Hello,

We are trying to migrate several dozen clients from Avast Pro to Avast Endpoint. The clients are Windows XP and Windows 7.
We created a package, which installs perfectly to a cleanly installed Windows system. It registers to the EA server and the policies are set.

However, if we try to install the same package to a computer which previously had an Avast installation (Pro, 5/6/7, a bit diverse) the installation succeeds but the client does not register to the EA server.

The error we are getting (in the entAgent.log file):

[2013/10/11 19:28:18.154,5360] Obtained server IP address: 172.30.1.221
[2013/10/11 19:28:18.154,5360] Creating server connection socket
[2013/10/11 19:28:19.792,5360] Connection to server created with 0x00000000 error code…
[2013/10/11 19:28:19.792,5360] Connected to server…
[2013/10/11 19:28:19.792,5360] Last resident change:
[2013/10/11 19:28:19.792,5360] Space available at temp directory: 1071812608 bytes…
[2013/10/11 19:28:19.808,5360] Agent installation GUID: a179102e-02ff-4355-93f7-f24210e87b99
[2013/10/11 19:28:21.804,5360] Unable to perform pop from server, error 0x7FFF0021 occured…
[2013/10/11 19:28:23.816,5360] Stopping CSocket::ListenThread()…
[2013/10/11 19:28:23.816,5360] Cannot connect to server, error 0x7FFF0021…
[2013/10/11 19:28:23.816,5360] Exception 0x7FFF0021 generated in CClient::PopupThread()

Of course before the installation of the package, we have removed the old avast product with uninstall, plus we ran aswClear.exe

Any help would be greatly appreciated.

thanks

Daniel

edit: We tried to install the package via remote deployment, or run the .exe from the computer itself, no difference, same error.

On the server, I can see the following entry:

[2013/10/11 19:27:00.450,488] Engine is not handled, probably out of licenses…
[2013/10/11 19:27:00.450,488] sqlFreeConnection with fReturnToPool=false (error handler)
[2013/10/11 19:27:00.450,488] SQL Server connection has been destroyed…

I guess that the Pro! installation is not removed correctly with the uninstall. As we only have Endpoint licenses, the server cannot accept the client. How can the bogus old Pro license be removed from the client?

Daniel