Random Foreest classification error

I have done all my pre-processing on Sentinel 2A in SNAP. With all the parameters set plus the ROI for each class ready for training and subsequent classification. when i say RUN in SNAP i get an error message …
bound must be positive…what could be happening

This issue is already solved here,

Please take a look at this post,

Thank you sir i have done exactly how it was suggested in this post and it worked perfectly well.

hlw @falahfakhri, i have classified(random forest classification) two images using snap, but the problem is that i can’t mosaic them, would you please tell me the way how can i mosaic image after classification.

Have a look at these threads please,

Multi size mosaic

Uniting two data set