Problem of multiple nonlinear regression

Hi there,

I did a linear regression for Y with multiple X, but the confidence level is low (R^2 = 0.45), so I would like to make a non-linear regression based on the linear coefficients. However, it gave me errors (Error using nlinfit>checkFunVals (line 649) :The function you provided as the MODELFUN input has returned Inf or NaN values). I tried different beta0 but it did not work, so I do not know how to deal with it.

I attached the m file as well as the variables (X: columns 1-14, Y: column 15) in excel, could you help me to make the non-linear regression? Thank you very much.