DB recovery using ontape

I am new to the utility "ontape". I hope somebody can explain to me what's going on. To get familiar with the tool, I created a dataspace and put data in it and created a level-0 archive using "ontape -s". Then, I updated one of the record and created a logical log archive using "ontape -a". For the testing purpose, I used UNIX files (not devices) to specify the destination for both system and logincal archive tape devices. When I try to do full recovery using those two files, I get the system archive recovered fine but I can't get the logical log to rollforward which means that I can't get any update after I created the system archive. Does anybody know what I am doing wrong ? During the recovery, I didn't get any error message. Kenji