It looks like you are using an obsolete version of NEWFF where the first input is minmax(input_n) instead of input_n.
However, even the latest version of NEWFF is obsolete.
What version of MATLAB do you have? Type ver into the command line
The current versions of MLP are
Regression/curve-fitting: FITNET(calls FEEDFORWARDNET) instead of NEWFIT(calls NEWFF)
Classification/pattern-recognition: PATTERNNET(calls FEEDFORWARDNET)instead of NEWPR(calls FEEDFORWARDNET)
Hope this helps.
Thank you for formally accepting my answer