function blockF ()
MessageBox ("/Maps/RMG/4939-1686-2472-1326/preymushestvo/block.txt");
end;
Trigger(REGION_ENTER_AND_STOP_TRIGGER, "block", "blockF"); - this is the script.
Try removing the slash before the word Maps.
MessageBox ("Maps/RMG/4939-1686-2472-1326/preymushestvo/block.txt");