I am attempting to expand some volumes, and getting the following error message.  I've done two others and they completed successfully.  Any insight to what active sessions could hinder the expansion?  How to resolve?

C:\Users\A1195732-3>symconfigure -sid 452 -cmd "add dev 891C:8933 to meta 308F, protect_data=TRUE, bcv_meta_head=8934;" prepare

Execute a symconfigure operation for symmetrix '000195702452' (y/ ) ? y

A Configuration Change operation is in progress. Please wait...

    Establishing a configuration change session...............Established.

    Error occurred while Defining change number 1:

    The requested device has active sessions

    Terminating the configuration change session..............Done.

The configuration change session has failed.