Hi, I'm having trouble importing my skeleton into unity.
When I move everything over into Unity, I get the following message
and when I try to add the atlas anyway, I get this 
This is the attachment in question

and it does exist in my files
and here it is in the .png created during exporting
I've tried re-meshing the attachment, deleting and re-adding it, but I still seem to get the same error message that only shows up during debug
Admittedly, I'm but a humble artist, and it's my programmer husband who is doing a lot of the unity-side of things, but he also has no idea what this could all possibly mean, so I was wondering if anyone here was able to put the pieces together and tell me what I can do to fix this. Thank you!