ATIh2014 error , System request acces to an increment version not yet created.

I had 3 BU-sets (incr BU). Set 1-2 had 1-9 files , ie 8 increments and one full. The latest set had 1 full and 3 increments.
I now erased the oldest set manually.
When I now made a additional BU to the latest BU-set ( with 1 full and 3 incr.) after some minutes the BU process halts and I got an error message:
" Failed to open backup H:\4Acr-BU Bjolen 6 data+sys\4Data BU\LöpBU_Wdisk\BU-W--H_inc_b21_s5_v1-2.tib. Make sure the backup location is accessible and contains all versions of the backup. This backup may also be corrupted " .
The system asked for a version "s5" but this has not yet been created and was the one that I intended to create. The error code in the log was useless.
Can anyone please help me with following:
- Isn't ATIh looking at the current BU-set and is latest increment number when giving the next increment a number.
-If not where can I find the actual numbering in ATIh for this BU so I can correct the error.
-Can this be a Bug in the program, to me it appears so.
Looking forward to any kind input/answer to clarify the issue.