Mr.Hamdy Sadek,
This is the answer i received from another user and it solved my problem.

There are many ways to work around this problem. First, try making your object Opaque and not transparent, and then 'Bring it to front', then try opening the Color Palette toolbar, click on foreground, choose black, click on background and click white. Try to print ( even if you still don't see the object in edit mode ).
If this doesn't help, open manually the report file ( i.e use yourreport.Frx ), find the object in question ( it's in the EXPR column ), and set the columns PenRed, PenGreen and PenBlue to 0, and then the columns FillRed,FillGreen and FillBlue to -1. Save the record ( i.e exit the browse window with Ctl-End ), rebuild the project, and try printing.
If this still doesn't help, you can create an opaque white shape that you can send to back behind your object ( this also did it to me once ).
Last, if this still doesn't work, set the background to DargGray, this will print for sure ( but you'll have a problem though, if you're using color output ).
Hope this helped