Unable to move shadow storage onto a different volume

Running Windows 7 Pro x64 and entering this command:

vssadmin resize shadowstorage /for=c: /on=f: /maxsize=UNBOUNDED

I get the following error:

Error: The specified volume shadow copy storage association was not found.

But this command:

vssadmin resize shadowstorage /for=c: /on=c: /maxsize=30GB

works fine.

I'm getting Event 25 in the event log:

The shadow copies of volume C: were deleted because the shadow copy storage could not grow in time.  Consider reducing the IO load on the system or choose a shadow copy storage volume that is not being shadow copied.

I'm just trying to follow the suggestion provided by choosing a shadow copy storage volume that is not being shadow copied.

How do I move the shadow copy storage to a different volume?

Thanks