Need help trying to make custom unit sprites work

[Erenussocrates]

Hey, I dug around desperately enough to find some cool stuff in this forums, and I've stumbled on some sprites.

The dragon rider and spearman in the attachment of this post are the two of them. I've even modified their number of panels to be the same as gryphon rider and axethrower, respectively, so that I won't have too much problem getting the animations work if I copy and paste their animation code. Even though I did copy the respective codes in anim.lua and changed the names accordingly, whenever I try to create a new unit and assign the animation and the sprite png to it, it fails. The game crashes whenever I attempt to start a campaign mission. I really need help with working it.

I tried to open stderr to see the cause of the crash, but stderr doesn't say anything.