I used "mě" instead of "mne" and it did not accept that answer. It shows "You used the wrong word." And there is no option "My answer should be accepted" in report. Isn't "mě" and "mne" can be used interchangeably?
It is strange, because it is definitely failed my answer. And the only difference was in this word. I'll try the next time again, if I remember.
I have fall into it again. I think it is so because is a "Type what you hear" question. And probably it really pronounces "mne", so it expects only this form.