Script error when dropping slingloads

[Humbug]

As the title implies I (as server host) get a script error the exact moment somebody drops a slingload. Tested multiple times and it always coincides with sling load drop. Before actually putting sling loads in this mission I have never seen a script error before. A copy of the mission I'm using can be provided if that would help bug tracking.

 

Here's a screenshot of the error in question:

[thinkr]

post mission please

[Humbug]

Mission attached.

Weapons Training MA-1.5.miz