program stops due to lsqcurvefit multistart failure

I created a long code that fits some data to a model, I have several sets of data to check my program I tried with 4 sets of data and it is giving good results and the code is working fine for them, in the last 2 sets of data the program returns the same error each time as follows

Error using snls (line 47)

Objective function is returning undefined values at initial point.

lsqcurvefit cannot continue.

Error in lsqncommon (line 150)

    [xC,FVAL,LAMBDA,JACOB,EXITFLAG,OUTPUT,msgData]=...

Error in lsqcurvefit (line 253)

[xCurrent,Resnorm,FVAL,EXITFLAG,OUTPUT,LAMBDA,JACOB] = ...

Error in fmultistart (line 32)

Error in MultiStart/run (line 256)

           [x,fval,exitflag,output] = ...

Error in Main (line 45)

[betasupc,ssesupc] = run(ms1,problem1,70)

Caused by:

    Failure in evaluation call to the local solver with user-supplied

    problem structure.

what could be the problem noting that it is working fine for the other data?. Thanks in advance