adobe wont print, no page selected

I am experiencing a problem with my Windows 64 bit workstation, trying to print an extra-large (60"X90") poster to my HP Plotter.

The Print dialog box shows the project divided vertically in three 36" wide strips, which should work out with my plotter loaded with 36"paper.

But when I select "Print" from the print menu, I get the Adobe "i" message "The document could not be printed" followed by another "i" message "There were no pages selected to print".

I checked, and of course the "all" button is selected in "Pages to Print