We actually do not support that *.pbm file format. That may be something we move to down the road, but for now the support is not there... The image formats that we can work with are BMP, JPEG, TIFF, PNG, AIPG (our own internal file format). You can refer to a document in our Developer's Zone that details this a little more... Go to http://zone.ni.com/devzone/conceptd.nsf/webmain/87B303368E4B55788625682600620419?opendocument.
Best of luck to you,
Jim Laudie
Applications Engineer, National Instruments