MLE program troubleshoot for the error "the pdf function returned negative or zero values"

i have the following code and the error msg is

"Error using mlecustom>llf_pdfcdf (line 440)

The PDF function returned negative or zero values."

what is to be changed to get the lamda value?pls help me

X=[0;1;1;1;1;1;1;1;1;1;1]

Y=[0;0;3.16060256660987;4.32332341640756;4.75106456578097;4.90842176024353;4.96631024416752;4.98760622991804;4.99544058622424;4.99832268520062;4.99938295029261] t=[0:1:10]'

data=[X Y]

fn_mle=@(lamda, X, t) lamda(1)*(1-exp(-lamda(2).*t)).*X

phat=mle(data(:,2),'pdf',fn_mle,'start',[5 1],'lowerbound', [0.01 0.01], 'upperbound', [100 100]);

Answer 1

[sun]

Use the 'lowerbound' and 'upperbound'

http://www.mathworks.com/help/stats/mle.html