I have just installed FCKeditor 2.5 on ZC 1.3.8

I can edit and format product descriptions which show OK in the zencart products description and preview, but when updated I just get basic text on my website. All I can do is add or delete text?

I had some errors initially and tried different versions up to 2.6.4 Maybe I have not uninstalled all the files I need to from previous versions?

I also have quick updates 2-04 and dual pricing add ons.

Please help.