I have to thanks everyone for your help. The problem was solved by changing the Pterm limits from 19 to 17 on the options. Don't ask me why. There were other things that have to be solved in between like three state buffers don't work if they are not connected to an output pin. The original schematic was done with them but they didn't work in ISE. It just tells you that the signals that you have connected to them are not used an for that reason they will be eliminated, but it never says, you are using a component that is not allowed in that position. Other that, the issue is now resolved thanks to Jonathan Heslip that is the person that was taking care of the web case I open for this issue.
Thanks everyone again for your ideas and help.
Enrique capone
