The cross-section isn't changed after applying rapidity cuts

I generated a process

p p > w+, w+ > ve e+

for sqrt[s] = 13 GeV first without any cuts (i.e., setting min pseudo-rapidity of charged leptons to 0 and maximal to -1), and second with pseudo-rapidity cut eta_min = 0.9 and eta_max = 1.6 for charged lepton, and similarly for electron neutrino (with pdg code 12). The resulting total cross-section, however, hasn't changed at all: its central value is 9114 pb for the case without cuts, and 9106 pb for the case with cuts. I don't understand what is a reason for this, since expected relatively strong suppression.

Can you please clarify it for me?