Yes I fully understand what’s happening here.
 
Generally this happens when you eventually play an opponent who has a good defence and good anticipation. The key here is to remain calm and mix the pace of your smash. You should also consider whether the real difference is not your smash but the better length your opponent is hitting.
 
If you ask any professional player, and many good standard players they will tell you that you can’t expect to win many points by smashing from the back line. You have to vary the pace, angle, placement of the smash to get a weaker reply from your opponent. The change of pace can sometimes cause them to mis-time their shot and present you with a mid-court/3/4 court opportunity. These are the shots that you’re really trying to kill.
 
Have a think what really happened because I suspect the problem does not lie with your smashing ability.
 
Paul