FCMclust validity measures do not vary even when I change the weighing exponent (m) value

I am using the 'FCMcall' function from the "FuzzyClusteringToolbox_m", I have analysed that the validity measures (SC, S, XB, etc) and the partition matrix values, only changed when the number of clusters are changed (e.g. 2, 3, 4,.........). But, the values of validity measures and partition matrix do not vary when I change the weighing exponent, m (param.m).

I would like to see the effect of varying number of clusters as well as the weighting exponent to obtain optimum number of clusters.

Is there some bug in the function? that's why there the validity measures are insensitive to the weighing exponent.

Please suggest a solution to fix this problem. Thanks