Adobe Acrobat 8 Professional combining pdf files

[Cynthias55979817]

I recently combined 4 different sets of architectural plans with Adobe Acrobat 8 Professional. Two sets combined perfectly with the architectural seal. The other 2 didn't. When you combine as a package it insists whoever tries to open it that they must download new software. I don't want to make people download to open these files, especially when it worked for 2 sets and I combined both the exact same way. What can I do differently to get the digital seal on the other 2 sets?