SNMP not monitoring all Local Disks

SNMP not monitoring all Local Disks

I have a 64bit windows 2003 server that i have the free disk space in MB monitor turned on in OpManager. Opmanager is only displaying 2 of my 5 disks. Anyone have any ideas as to why this is happening. Also getting an error on the top of the page when i add that monitor that it is unable to draw the graph.
Thanks
Mike

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