Unable to upload to Steam Workshop

[Dovahkiin]

I tried updating the mod to the workshop but the previous mod was locked. It says "Violation of <Steam Community and Content Guidelines>".

When I asked customer support the reply was "The content in question was removed by the game's developer."
Then when I upload to the workshop with the new file content, I get "failed to update workshop item, result = 15".
I feel very confused and kindly ask for your help.

[Beard]

Does your mod have all the correct files in the correct place? As based on the ModTemplate mod?

[Dovahkiin]

4 hours ago, Beard said:

Does your mod have all the correct files in the correct place? As based on the ModTemplate mod?

Yes, I did it in the correct order - just like in the ModTemplate. I asked my friend to help me log into his Steam on my PC and tried uploading the same files and it worked.
Now the mod problem is solved, but I'm still wondering why the previous mod was locked, and why "failed to update workshop item, result = 15" appeared.