Failed scoring functions result from ROC curve

Hi,
I'm using DS 4.1, DS created for me new ligands by running Fragment replace, i chose 3 different fragments to replace so that means i got 3 output files. When i docked all the ligands created in the 3 output files vs docking 3 different output files i recieve different results, the scoring is different and the ROC analysis returns a fail results for all the scoring functions vs a good to excellent when it's 3 separete file.
Can someone help me with this?
Many Thanks
Anat