Sprite gender issues, male invisible, female visible [4thGen]

Im editing a pokemon diamond rom currently, i am replacing smoochum and jynx (mainly because they interest me the least) with my custom 6th gen sprites, bergmite and avalugg. Everything has been sorted stats/names/description wise however the issue im having is this.

Both male versions of the pokemon ive added display as an invisible sprite with a shadow below it when met in the wild, when caught or attempted to catch; both display a glitched image of the background palette, no sign of the actual image of the pokemon.

However, both the FEMALE versions display perfectly, well as far as i can tell, both in party/pokedex etc etc.

Why is this?? Is something going on that is pulling a different sprite for the male version as opposed to the female version? I know both pokemon ive changed are 100% female, but why would gender effect the display of the sprite, or am i missing something really obvious?

Thanks in advance.

This better fits the ROM Hacking forum. Pixel Art is a place to showcase your own pixel work and gain feedback on it from the community. Please read the rules. Here's a link to the ROM Hacking forums.

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