Media Not completely overwriting on BE 2010R3

[3s1k]

We are running BE 2010r3 on SBS 2011. We have 7 rdx tapes that we rotate. Lately I notice some disk will not overwrite some of the data even after a successful full backup. I included an image so you can see it says it's overwritable but BE is asking for me to insert new blank media.

I put this tape in last friday and ran a complete full back up without issues. Monday morning I check backups and the incemental job is "loading Media". I check the Media tab and it shows roughly 100gb of overwritable data as well as Protected data from the recent full backup . I'm setting the disk that give me this probablem aside and as of now there are 2 disks. 

Any ideas?

Daily backup overwrite protection is set to 1 week

Full Backups are set for 2 weeks

Append Period is set to Infinite - I read this in another post

Also tried going to Tools>Options> Media Management> Setting Media Overwrite options to "Overwrite scratch media befor overwrrting recyclable media".

[3s1k]

Any ideas? I'm stuck on this one and backup tapes need to be changed mid week because the old data isn't being overwritten.

We don't have to purchase new disk as they are expensive.

[pkh]

Does your job specify Overwrite?

Your RDX is considered a disk media, not tape and as such, you should not use append.