Deconvolving two vectors produces a single number (not a vector)

I am trying to deconvolve the auto-correlation of my source wavelet (Ricker wavelet) from my receivers responses. Now if I deconvolve the source wavelet out of the response I get a vector back and the results are correct. When I try to deconvolve the auto correlation of the source wavelet from the response I get back a single number (not a vector)

s_t    = smax*(1-1/2*w0^2*(t-ts).^2).*exp( -(1/4)*w0^2*(t-ts).^2 ); % Ricker wavelet
xCorr = xcorr(pR_t(:,1,41),pR_t(:,41,41));    % Cross correlation
aCorr = xcorr(s_t);             % Auto correlatioin
G = deconv(xCorr,s_t);          % This works
G = deconv(xCorr,aCorr);   % This gives back a single number

All vectors here are of the same length. Of course you would not be able to reproduce the problem because you don't have the other information (frequency, time, synthetic seismic ... etc). If I include every thing it will be too long and i'm not sure if this is allowed.

any idea what might be causing this ?