derive a new class from the Uniform class

[Steve67]

Hi, 

I need to derive a new class from the uniform class of the type: TMainForm = class(TWebSecureForm)
The TwebSecureForm class (TWebSecureForm = class(TUniForm) is defined in a PlexaWebSecureForm unit and has been added to the uses of the Main
It seems that everything works correctly, the project compiles and also runs without errors but when I close and reopen the Main unit this error appears and I can't understand why

 

It's possibile derive another class from class Uniform ?

Thanks for any help