  We revisit the momentum independent many-body t-matrix approach for boson
systems developed by Shi and Griffin~\cite{sg} and Bijlsma and Stoof~\cite{bs}.
Despite its popularity, simplicity, and expected advantage of being its
applicability to both normal and superfluid phases, we find that the theory
breaks down in the normal phase of bosons. We conjecture that this failure is
due to neglecting of momentum dependence on the t-matrix.
