up-down control

I am writing a user mode printer driver for windows 98
Also i am adding a property sheet with some radio buttons , edit
box & Up-Down(Spin) Control
Every thing is fine.
Control is also coming to UDN_DELTAPOS notification sent by the
up-down control.
The problem is:
when i typecast the lParam value to NM_UPDOWN structure, i am not
getting iDelta & iPos data.
when i try to access these values it gives Invalid Direction. But
the first value i,e
NMHDR hdr is comming proper.Rest 2 values are null.
i will just add my code snippet
pNMUpDown = (NM_UPDOWN FAR *) lParam;
NMHDR hdr = pNMUpDown->hdr ;
int delta = pNMUpDown->iDelta ;
int pos = pNMUpDown->iPos ;
Can anybody tell me what could be the problem or where i am going