Why can't I 'Edit merged document' on an iPad but I can do it on a Mac?

Why can't I 'Edit merged document' on an iPad but I can do it on a Mac?

Hi, I can successfully edit a merged document on a Mac but when I am logged in on my tablet (iPad) it comes up with an error message saying 'invalid address' and it doesnt come up with the usual tab options at the top of the screen.. ie: File

Help please...