Includetext changes document format

I am making a large document based on several single documents using
Includetext. On one of my pages, the formatting in page set up looks the
same as the original document, but the last line of text shifts to the next
page in my new larger document. I can't figure out why it is doing this and
don't know how to fix it since it looks okay in the original document. I
appreciate any help!