As per the issue description mentioned above, you are facing issue when trying to sign apdf as you are getting black screen when clicking signature, is that correct?
Could you confirm if its a digital signature field on a pdf form you are trying to sign?
Also, try changing following setting:
Launch Reader/ Acrobat > click Edit > Preferences > Signatures
Creation & appearance > More , uncheck the box next to use modern interface for signing documents.
Click OK and try again.
Also, let us know the application you are using to open the pdf - Adobe Reade or Adobe Acrobat?
Operating system you are using?
Have you tried signing another pdf using your certificate signature? Does that work?
Let us know if you need any help.