im createfield symtax error

When I run the following im command I got "*** Error creating field Xxxx_Xxxx Xxx ##: syntax error"

im createfield --hostname=mks --type=date --description="Xxxx_Xxxx Xxx ##" --computation="XXXX_Xxxx Xxx Xxx Xxxx" --storeToHistoryFrequency=never --nostaticComputation --displayName="Xxxx Xxx ##" --name="XXXX_Xxxx Xxx ##"

The computation parameter is another Date field that is already created.

I'm using Integrity 2009 SP5 AIX.