You are checking collision with the body parts and it gives you the body part id. Then you are dismembering a joint using the body part id. You need to check collision with joints instead of body parts to get the correct joint id.
[18:04:54] <aracoon> Eureka is a powerhungry fag
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[13:13] <Eureka> also dota is kinda for pigfuckers
[13:13] <jalis> ban eureka
[13:13] <jalis> thanks
lol i loaded the script and went to multiplayer...... and my opponent had the laser and when it touches me... I DISMEMBER! BUT THE OTHER PLAYER CANT SEES ANY!