Converting XPS files to PDF

Hi,

I try to convert XPS files to PDF and I get this exception:
"System.ArgumentException : The ImagesSource /Documents/1/Resources/Images/PIX_0_0.wdp was not found".

I noticed that problem occurs when image files are split into pieces (PIX_0_0.wdp is a directory containing [0].piece [1].last.piece files).
It seems the problem occurs only with split files in "Image" folder.

Thank you for your help.