Basinhopping only returns fit parameters of first iteration even though other minimas are lower.

[Maxim Simmonds]

Dear all, 

I dont know if there are minimal requirements for a code or so. Attached the code that I use. In short, when following the residual values and the accepted variable using a callback function, I see that the chi-squared for the fit results is always the first iteration of the algorithm. I am not sure if it is linked to the callback function that I use to follow the advancing of the data.

I am not sure how this is the case and am struggling to find a suitable answer. Can somebody help? thanks!

PS: I apologize in advance for my ignorant coding.