ROI's don't have displayable labels. If you want to create text labeling a portion of your image, the Overlay vi's can be used. They are used to create custom labels and outlines for ROI's etc. A good example of using the overlay vi's is in the Pattern Matching example:
C:\Program Files\National Instruments\LabVIEW 7.1\examples\Vision\2. Functions\Pattern Matching
I attached a screen shot that shows the sub-vi that has all the overlay vi's to create a box w/ cross hairs for every pattern found. Something similar to this could be made with the IMAQ Overlay Text.vi for labeling ROI's.
