strike plate problem

[nellie#5]

I have just installed a new door knob on an old door. After much frustration and ordering a special part, I got the knob in. Now the strike plate doesn't seem to fit. The door closes, but won't hold securely. Any advice would be helpful.

[HayZee518]

the old door had a mortise lockset and its strikeplate had a rectangular cutout for the latch and a smaller similar shaped cutout for the lock deadbolt. a new passage lockset has a strikeplate shaped like the letter D with an extra cutout on the D side with a notch for the primary pin. you need to remove the old strikeplate, fill in the openings from the old plate, then drill out a clearance for the new bolt. the strikeplate may need to be mortised into the door frame with a chisel so it lays even with the door jamb.