Why do I get this error message when trying to add or copy stylesheets

[djkirstyjay]

Whenever I try to copy an existing stylesheet in order to make a new one, or create a new one from scratch, a red block appears at the top of the page which says 'error inserting stylesheet' and that's it... no other info.

I have tried reuploading the entire admin directory with files from a site working on the same version (1.0.8 Kona) of CMSMS that IS working.

I have also tried changing the permissions on the addcss.php and editcss.php files to 755.

I have no idea what is going wrong! I could add the stylesheets via phpMyAdmin if need be, however it would sort of defeat the object of the CMS if I had to....

Any ideas folks? It's stumped me! (Mind you that isn't hard  )

Thanks in advance! 

PS: I can edit existing stylesheets, no probs.