First, thank you for including data and runnable code.
Second, it appears to run fine here (see below).
Try updating your peakfit.m by downloading the latest version (it's attached to this answer too):
I just downloaded that, and I notice its line 1610 is not the same as the line 1610 reported in your error message, so probably getting the latest version will fix the problem.
unzip('HB2B_2506.zip')
%% Inputs
i=0;
for fna= 2506 %2506:2520
fname=sprintf('HB2B_%d.h5',fna);
i=i+1;
NumPeaks=1;
NumTrials=15;%the higher the number, the better the fit is (but slower), typical value: 10
BaselineMode=1;%0 no baseline, 1 linear, 2 quadratic, 3 flat(not working yet)
peakshape=33;%Ps. Voigt
window=8e-12;% center +/- (window/2) corresponds to the fitting window
center=1.09e-10;
fwhm=1; start=[center fwhm];%first guess (ignore=0)
fixedparameters=[peakshape start(1) start(2)];%specifies fixed peakshape, pos, width (ignore=0)
plots=1;%plot for each peakfit
extra=1;%all peaks with same shape: use extra=1
%% Code starts
info = h5info(fname);
theta2 = h5read(fname,sprintf('%s/2theta',info.Groups(5).Name));
counts = h5read(fname,sprintf('%s/main',info.Groups(5).Name));
wave=h5read(fname,'/instrument/monochromator setting/wave length')*1e-10;
d=wave./(2.*sin(theta2./2*pi/180));
signal=[d,counts];%d-spacing
%%%%% Error in the bottom line %%%%%
[results,resultserr]=peakfit(signal,center,window,NumPeaks,peakshape,extra, NumTrials, start, BaselineMode,fixedparameters,plots);
%%%%%% Error%%%%%%%%%%%%%%
pos(i)=results(1,2); int(i)=results(1,3);
w(i)=results(1,4); area(i)=results(1,5);
err(i)=resultserr(1); r2(i)=resultserr(2);
end
