I didn't mean in this part of your event sheet. you are checking if gnumberblocks is less than three here, but there aren't any actions in the whole of your event sheet to change the value of gnumberblocks.
when numberblocks are destroyed, gnumberblocks should change, but it doesn't as far as I can see.
make a new textobject on your layout and every tick set its text to gnumberblocks. see if it changes, for if it doesn't that's the problem.