What level range are they doing this in?
Caster bots are hard coded to melee up to level 12. After that, then they only cast.
If you're running your own server, you can find the limit here:
https://github.com/EQEmu/Server/blob...r/zone/bot.cpp (void Bot::AI_Process() ~line 3564)
There's a couple of checks in there that can be altered.