Adobe Acrobat X Pro - Suddenly when combining four documents, document 1 does not show, but instead document 4 which is repeated at the end. I tried combining using the original Excel sheets and the the corresponding PDFs.... Impossible !

Using Adobe Acrobat X Pro, I am suddenly unable to correctly combine four documents A, B, C and D. D appears first, then B, then C and then again D. I tried combining from the original Excel sheets or with the corresponding PDFs... Same result.

What is happening and what should I do to correct this problem ?

Thanks for your help.