Crystal Reports V10 Deployment problems

I have written a C++ windows application (not .net) that uses crystal reports. Previously I had CR8 and everything worked 100%. Now with CR10 I had to change to RDC and it's working fine where the complete installation of CR10 is done.
I have written a setup program with installshield express 5 (or via Visual Studio 2005). After running the install on another PC (in my case a WindowsXP virtual PC) the program opens the report without any error but the report window is blank.
I included the following merge modules: rdcruntime, reportengine and even rdcdesigntime

Any idea anyone?