Hello ad welcome ^U^
The most likely cause for the Hatch button not working is that there is already a pet with the name you're trying.
Names are unique on Rescreatu, that means, for example, there cant be two pets named Bob.
If a name is already taken the box and letters will turn red and you wont be able to finish the hatch.
If a name if free it'll turn green.
You might have to get a bit imaginative with names ^^""
Ahhh yes, that's a pretty frustrating issue.
If I understand correctly may users have had that issue before.
the points below might help:
1.) make sure you press "SAVE" once you've finished changing clothes
2.) hard refreshing always helped me. F5 is the hard refresh button (i'm not sure what it is for macs or how to do it on tablets and mobile devices)
If these fail you might have to send in a support ticket.
To send in a support ticket go Rmail> click the support ticket tab
Hope these help^U^