disappearing numbers from PDF graphics

[Zimerman Orly]

Hi All, 
I have a strange problem with one of the graphics in my PDF file created from FM7.0.
I used CorelDraw to create the graphic,and then exported to a WMF format.
I create the PDF using Distiller and Acrobat 5.0. 
 
Problem, 
Two sets of numbers in the graphics appear at will: sometimes you see it and sometimes you don't - depending on the magnification size. I don't really care about it on-screen, as this is for printing a small guide. But when I printed the page, I also lost those numbers, although you can see them on screen. 
 
Does anyone know what is going on ?
TIA,
Orly.
 
Orly Zimmerman
Technical Writer
Tadiran Telecom LTD
orly.zimerman at tadirantele.com
+972-3-926-2023