Let F=(F_n)n be an l-adic sheaf on X{et}$F=(F\_n)\_n$ be an $\ell$-adic sheaf on $X\_{et}$, for a variety X$X$ over an algebraically closed field k$k$ of characteristic not equal to l$\ell$. Does the presheaf sending U$U$ to H^i(U,F):=\lim_nH^i(U,F_n)$H^i(U,F):=\lim\_n H^i(U,F\_n)$ sheafify to zero?