The calculation for tolerance deviation in LK-DMIS depends upon the sign of the nominal. If the nominal is + we do subtract the actual from the nominal. If the nominal is negative we change the sign of the difference value. This is because inspection personnel typically are checking to see if a dimensions is larger or smaller than nominal. This would explain why your difference is -1.3 we are indicating that the dimension is shorter than it should be.
Historically, LK used to output the difference value as a mathematically correct value but this confused many users and so we changed it. However, as you cannot satisfy all of the people all of the time, we made it configurable!

If you start the DMIS application, and then click the UTILITIES>CONFIG>MORE buttons you change the TOL/CORTOL difference from Nominal to Mathematical. This should cause the -1.3 to be reported as +1.3

Regards
Keith Morton