its normal for that hold. you see, the club has carry distance and run distance. the reason you are 18 yards short is 2 fold:
1. that green is slightly uphill so it plays longer
2. its landing area is 4-5 ft below the green, so anything landing on it without GOOD power will stop 18 yards short, like you noticed.
next time try to hitting full power and land 6-7 yards further, it should release then. or come from left or right side (not directly at the flag)