TypeMock 4.0.3 Net 1.1 version and AutoDeploy

Hi,
TypeMock 3.7.1 was working fine in our build server with CCNet, NCover and Nunit and there were no issues. In our build server we do not install any tools.

Recently we attempted to use TypeMock 4.0.3. Our projects refer to the Net 1.1 version of the TypeMock.dll in the Net11 folder. But still we get System.IO.FileNotFoundException and invalid file format errors as below. It looks like it is trying to use the Net 2.0 version of TypeMock.

Currently we have reverted back to 3.7.1 version. Anyone seen this issue?

Errors:

F:uildsourceMTA 4.0sourcedefault.build(304,4):
External Program Failed: regsvr32 (return code was 5)
The format of the file 'TypeMock' is invalid.
Nested build failed. Refer to build log for exact reason.

Internal Error: System.BadImageFormatException
The format of the file 'TypeMock' is invalid.

at d.b()
at TypeMock.NAntBuild.TypeMockRegisterTask.ExecuteTask()
at NAnt.Core.Task.Execute()
at NAnt.Core.TaskContainer.ExecuteChildTasks()
at NAnt.Core.Tasks.IfTask.ExecuteTask()
at NAnt.Core.Task.Execute()
at NAnt.Core.Target.Execute()
at NAnt.Core.Project.Execute(String targetName, Boolean forceDependencies)
at NAnt.Core.Tasks.CallTask.ExecuteTask()
at NAnt.Core.Task.Execute()
at NAnt.Core.Project.InitializeProjectDocument(XmlDocument doc)
at NAnt.Core.Project.Execute()
at NAnt.Core.Project.Run()