problem with curve fitting in Matlab

Hi all,

I'm trying to fit a data with a function called "refl_pp" that I construct myself. I tried to use fit routine:

ffit = fittype('@(A1,A2,k1,k2,Step,t,t0,w)refl_pp','independent','t','problem','Step');
F=fit(t,data',ffit,'StartPoint',[0.0005 0.0001 3. 1. 0.1 3.3],'problem',Step);

As a result I get an error message:
??? Matrix dimensions must agree.

Error in ==> fit at 486
errstr = handleerr( errid, errmsg, suppresserr );

Error in ==> TiSe_phonon_fit at 37
[F,gof]=fit(t,data',ffit,'StartPoint',[0.0005 0.0001 3. 1. 0.1 3.3],'problem',Step);

I had no problems, if I pass a function as a string in fittype, so it seems like I handle the function not correctly.
Does anybody know what the problem is?

thank you in advance, katja
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