Can you also translate Δεν υπάρχει απόδειξη για αυτό as 'there is not a receipt for this'?
If it's just been added, great, if not then for some reason it's not working as this answer wasn't accepted (it was a strengthening exercise).
"there is no proof for this" is currently marked as incorrect, general strengthening on web. I'd say that "of" and "for" are fairly interchangeable in this context in the English.
"There is no proof for that" is not accepted but sounds better to me than "of". Is there a reason for that?
Correction from me.
"There is not a receipt" was not accepted but i think it should be
my answer: There is no proof about it. I believe that my answer is correct