turboPres -
The error codes should be in the documentation, as well as in the file "nivision.h", for future reference.
That error code means "Incompatible image type", which probably means
that you're calling imaqColorThreshold() with a dest image that is not
of type IMAQ_IMAGE_U8, or a source image that is not of type
IMAQ_IMAGE_RGB or IMAQ_IMAGE_HSL.
Hope this helps!
Greg Stoll
IMAQ R&D
National Instruments
Greg Stoll
LabVIEW R&D