VTL cannot vary on in AS400 after fiber card replacement

Hi,

Last month we have replace fiber card because new SAN switch only support minimum 8Gbps speed. But after we replace the fiber card, the we able to vary on tape library(TAPMLB03-Changer) but cannot vary on the virtual tape devices. Error message mentioned device currently vary on in other system. But the VTL is only assigned to that particular system. Any one has idea for this ?

Thanks in advance.