Backup tapes not appending on backup exec 2014

I have the tapes in a media set that has overwrite protection period of 3 week and the append period set to none with infinite allow append.  I remove the used tapes once a week.   The tapes are not appending first.   It seems like it uses the scratch media first before appending the tapes.   I have an lto6 tapes and only using 10% or so at the time of week when I take out the tapes for the week.  I have backup exec 2012 with the same set up and it works there.   The only difference is that I back up to disk then immediately to tape on the 2014.