WARNING!You can kill your U960... if you tell us (or pm me) what you want to do?

Then maybe we can help you.
For Multi Image tab you need
multiple files, you can choose them under advanced...
pbl, qcsbl, oemsbl, amss and few more...
Again. You can kill handset with wrong files or wrong settings!So only JTAG Hardware would help to reanimate...
BUT for U960 not in public available... AMSS could be extracable from Firmware *.bin file or from dumped Firmware...
But NOBODY shared yet the whole Firmware for study

Best Regards
P.S.:
You could try QPST Memory Debug App...
If you press Get Regions---> normally handset change into DL Mode...
BUT if Windows Driver not complete (but there are floating generic Qualcomm Driver in Internet around).
OR Samsung protected there U960 against investigation.
Download Mode is powerfull for write AND READ Memory.

If not protected/disabled from manufacturer...