What are the requirements for the "incorrectly regarded as goof" category?

Hi, I'm new at making posts like these, so bare with me.

A few months ago, I noticed a mistake in a goof someone had posted for the movie "Project Amlanac".  (I won't say which one specifically, as I still hope to correct it myself.) I have tried off and on since then to correct it, but each time I receive the following message:

"Your contribution has been declined. Please review our submission guidelines."

The problem is that the guidelines say next to nothing about what I should do when correcting someone else's post, and I have no idea what I'm doing wrong. I have tried simply adding more information while modifying the original statement only slightly, and also adding my information without changing a word of the original. Once I even made a note in the comment section giving the exact time for the scene that supported my conclusion.

I'm flying blind here. Could someone please tell me what is required for this sort of thing?