DSR 11 won't record DV tape to its end
You need to use longer tapes. The DER-11 is a DVCAM deck which when recording, uses a faster tape speed then mini DV. Think of your older VCR's. They had SP, two hours, and EP or SLP, which would be six hours. The SP speed would give a better picture. DVCAM is more like an SP recording except digital and a lot better. More information is laid down on the tape.
You'll have to jump up to the full size DVCAM tapes in order to record the full hour.