Can't use Cell- and Padstack Editor (faded tool/ tool not active/ can't click the tool)

Hello,

I have installed the version 7.9.5 of Expedition on Windows 7. In the part editor I can only create parts, but no padstacks or cells. I can use existing cells (in Pin Mapping) but not create them. I used a preinstalled library (HLA CentralLibrary) and made some additional parts. But now I can't create the needed padstacks/cells.

Please can someone help me? Write, if you need additional info.