Command isn't executing correctly within a command block

The command doesn't execute correctly from the trigger location I set (-481 4 307), it only triggers from the command block.

I want the command to summon lightning when a player is within 2 blocks of -481 4 307 to strike lightning at -481 4 294 so I wrote in the command block: /execute @p [r=2] -481 4 307 summon lightning_bolt -481 4 294

The lightning hits the right location but it triggers 2 blocks from where the command block is hidden -481 3 327 and not the first set of co-ordinates before the word summon.