Fitting gaussian to a seriers of spectra

Hi, i'm using this code

%%Read data and fitting
[m,n]=size(A);
k=1;
for i=1:(n-1)/2
wl=A(:,2*i-1);
abs=A(:,2*i);
yy=smooth(abs);
[gaussfit]=fit(wl, yy, 'gauss1');
figure(1)
plot(gaussfit)
legend('off')
hold on
[a,b]=max(abs);
index(k,1)=b;
maxima(k,1)=wl(b);
k=k+1;

end

figure(2) % plot(index,'o') % hold on plot(maxima,'o')

to fit the data in the worksheet A (are alternatively the x and the y of the spectra i'm analysing). Whit the first table i tried i worked fine but with the second one i gives this error:

??? Inf computed by model function.

Error in ==> fit at 443 errstr = handleerr( errid, errmsg, suppresserr );

I think the reason could be two: #1 In this new tables i have some negative values #2 Some curve are really "unfittable" by a gaussian (they are flat pretty much)

Considering i'm a matlab noob there is a way to solve this problem (that actually i do not even know what it is) Thanks mik