LTO tapes not compressing

[Bugs]

Got a bit of an issue with our ultrium 960 drive, whenever I run my monthly backup using backup exec 11d it doesn't compress the data, which I need it to do so it fits on one tape.

 

Weird thing is my weekly full backup works correctly, and I have even tried copying the job and renaming it monthly but, it still fails.

 

The only difference I can see is my weekly's are HP tapes and my monthly's are Sony. I have checked the compression settings and they are set to hardware if not otherwise software.

 

anyone seen this before? or got any ideas what's happening.