The maximum number of photos in a thread is ten, but when I put in ten in a thread a notification comes up and says I have added eleven, when I put in nine it is happy. Strange?
I see no other inclusions other than the photos. Is it the size of the photos causing the problem?

 

Are they metric photos? Maybe metric sized photos are larger...

 

I wonder if the website is counting the text as one of the posts. That could explain the messages you receive.

 

Dave, certainly no computer expert here but from another forum I participated with, the signature block counted as a photo, may be the same here. Keep those photos coming, this forum is a treasure of information.
steve

 

That is a good idea, I'll try that.
Got rid of the signature and no change.
I can have ten thumbnails but not ten pics in the post.