Help！ How can I change the program code to avoid mistakes cased by mle()?

My program code:

d=[ 0.2000 0.3000 1.0000 0.5000 0.2000 0.5000 0.1000 0.8000 0.1000]';

lgsp=@(x,m,b)(1/(1+exp(-(10*x-m)/b)));

phat=mle(d,'pdf',lgsp,'start',[0.3 1]);

The mistakes:

??? Error using ==> mlecustom>llf_pdfcdf at 443

The PDF function returned negative or zero values.

Error in ==> fminsearch at 195

fv(:,1) = funfcn(x,varargin{:});

Error in ==> mlecustom at 186

        [phat,nll,err,output] = ...

Error in ==> mle at 225

            phat = mlecustom(data,varargin{:});

Thank You!

ChangyiXiao