I am working to create a landcover classification map of an area that crosses several Landsat tiles and that I have limited reference data across the whole area (although I have quite a bit in one of the tiles). I was able to classify the tile with the most reference data successfully and would like to utilize overlap between the tiles to 'chain' the classification. I want to use the successful classification that is in the overlap area as the training data for the next tile. I assumed that I could do that by creating a resized image 'slice' of the overlap area on the classification and creating ROIs using the "Generate Random Sample from Ground Truth Image" tool to create a pixel training ROI for the classification classes. I am able to get the pixel ROIs created and reconciled to the next image, but whenever I run the classifier itself all that returns is a blank screen with all the pixels showing a value of "0-Unclassified". I am using ENVI Classic. Any ideas what I might be doing wrong or any suggestions would be greatly appreciated. ***Edit*** I backtracked a bit to try to determine if the issue was with the images, the ROIs, or some combination. I am working with a stacked image of multiple dates and bands. If I break it out into the various parts (one image thats all spectral bands (36 bands total), and several vegetation indices (6 bands and 18 bands) images, for the multiple dates) I can get the ROIs to classify the individual stacks (stacks 1, 2, 3) and on combinations of stacks 1&2 and 1&3, but not on 2&3 or when I restack all of the different bands (stacks 1, 2, &3) into a single image it gives the black screen output from the classifier. Running a seperability report on the various image stacks also works fine, but when I try the seperability report on the totally stacked image I get an error "Singular value encountered in calculation for ROI:Random Sample" for each of the ROI classes. The totally stacked image has a total of 60 bands and I'm using at least 250 ROI points per class, in case that matters. I also tried creating totally new ROIs in the image itself and had the same problem (individual stacks work, but not the complete stack). I tried looking for a better description and ways to resolve this error on-line and was unable to find anything. I've used this same image/band stacking procedure on other images/tiles without a problem.