2014 Revit dimension help please

Hi,

I am a beginner with revit, and experiencing trouble with dimensioning. While working on revit, the dimensions appear fine and work correctly. However when I go to print the file as a PDF, when I open the PDF, instead of showing as numbers
the dimensions just appear as square boxes, and I can't seem to change this. When I press print preview, the dimensions show correctly, it is just in the PDF file. However, I have tried with another file of just a rectangular room, and the dimensions show fine, so I am obviously doing something wrong on this particular file. I have attached the PDF file with the boxes showing.
Your help would be really greatly appreciated.
Many thanks!