NRPNs for Negative Ranges

Hi. in CTRLR I can easily use CCs that sweep from 0 - 127 to get Patch Tuning to sweep from negative to positive but NRPNS on the Part Structure like Tuning 114 is not working. Using your example in the manual I can get it to -13 putting 115 in the LSB number 38. But trying to set a data slider to sweep from -127 to positive 127 is not working. I’ve tried many combos of positive and negative numbers on the 6 MSB and 38 LSB and best I can do is get it to go from 0 to 127 then halfway jump to -127 halfway to 0. No combo of numbers I’ve tried produces the right sweep. Same issue with the Octave -2 to + 2. Is there a correct setup to affect these parameters for data sliders?

Thanks, Dan