Sometimes you calculate absolutely nonsense

Die_Schanze
Die_Schanze
Apr 27, 2017, 2:03 AM |
0
Here is a puzzle from Emms book where i tried hard to solve and finally haven't solved it:
White mates in three.
 
 
Sometimes it happens to me that i calculate with impossible moves (here it was 2... Ke8) or with pieces on their original place when they have moved somewhere else or are not on board any more. I have to keep an eye on that.
 
Any idea how to fix that?