I have been struggling to understand MARIE, the simulator for a while and have to create a program taht counts a number of non-empty memory locations in the line and when it reaches a cell that doesn't have a number in it skips the jump loop and outputs the number of cells that have non-empty memory locations.
this is the best answer I have at the moment and it won't read my skip condition:

LOOP,ADDI Y
LOAD Y
ADD ONE
STORE Y
SKIPCOND 400
JUMP LOOP
OUTPUT
HALT
Y, DEC 0
ONE, DEC 1

can anyone tell, or at least try to explain where I have went wrong.
thanks for any help.