BE can't compress data writing to tape

There is BE 2012 which according to daily schedule creates backup using the method "disk to disk to tape". A writing process to a tape run immediately after a disk backup finishes and in this case data written to a tape is compressed, rate of compression is about 2:1, so, everything is ok. I need to get additional tape copies every month to keep data in a remote location. As a result, I create additional job which should copy a last available backup from a disk to a tape and, of course, I enable options which makes BE used compression, however, in this case I get a tape without compression. There is another one noticeable thing which can be related to this trouble which is tape partitions. I separated one library cell as partition and use it when I try to make backup for remote keeping so as process of making additional copies can't influence on daily backup. What might be a cause of this trouble?