a bug on my server!!!

[JVC]

hello i run a antrix server 2.1.2 and i got a bug the bug is somtimes when a mob shuld be dead it just lay down and still hit but i cant hit it....???? can some help me repiar this bug??
:cloud:

 

[Fast_Elf]

Revision bug, Update your Revision.

 

[JVC]

but what rev shal i update it to?