Why does the objective function of fuzzy c-means algorithm become NaN in Matlab?

I am using the Matlab Fuzzy Inference toolbox to build an adaptive neuro-fuzzy inference system. I first use genfis3 to generate a FIS system and do the clustering, then use anfis to further calibrate the FIS system. The number of clusters N and exponent for the partition matrix U are randomly generated with minimal value of 1 for both variables. The result of genfis3 is like this

 and the result of anfis is like this

 Then I use another class of data to validate it, but an error was occured:

"Error using evalfismex

Illegal parameters in fisGaussianMF() --> sigma = 0

Error in evalfis (line 84) [output,IRR,ORR,ARR] = evalfismex(input, fis, numofpoints);"

Please advice me if anyone knows what's going on with this problem.