Un-X-tileable. Don't know why.

[4I Falcon]

As per usual, I'm having problems with my level wot is currently in construction. When I try to run the level, it gives me the following message:

"Layer 7 cannot be X-tiled because it is too large.

If you align the width of the layer on 4 tiles, it will be able to X-tile."

Considering the second line was kinda-sorta vague, I don't know what I'm supposed to do. Could someone help me out here plz thanks?

[Trafton]

Have you tried to reduce the size of layer 7?

That is a new error to me, but I think that is what it is trying to say.

[4I Falcon]

I don't think that was the problem. Well, it was... sort of.

I sized the layer down to 768 tiles, and it worked fine.It was obviously too large, as per the first line of the error box, but I still don't know what the alignment thing meant.