Modding (texture swapping) ranged creatures causing game to crash

[heyyouman999]

Been modding vanilla Heroes 3 with the DEF Editor that's contained in ERA, mostly swapping out original sprite works from the game with sprites that came from other games (for example, replacing the sprite of Pikeman with frames of certain characters from fighting games, etc.). When modding melee creatures it all works fine, but when modding creatures that have ranged attacks, a lot of times when testing the ranged attack in game, the game would throw a generic error then crash. So far I have modded Zealot, Arch Mage and Grand Elf, Zealot works fine. Arch Mage, when using "high/low ranged attack" (range attacking target above or below me), game would crash. For Grand Elf, any range attack would crash the game. I'm pretty sure it's not the problem with the frames I'm using, since I would swap all the frames of the creature with a working frame from a different creature, and then ranged attacks would still crash the game. I'm really at a lost now, just wondering if anybody knows what could be the problem?