In this paper we present simple examples showing the insensitivity of Dempster's rule of combination proposed in Dempster-Shafer Theory (DST) of evidence with respect to the level of conflict between two sources of evidences. Aside famous Zadeh's example on the validity of Dempster's rule of combination, it is shown that for an infinite number of cases Dempster's rule does not respond adequately to combine sources of evidence even when the level of conflict between sources is low. For a comparison purpose, we present the solution obtained by the more efficient PCR5 fusion rule proposed originally in Dezert-Smarandache Theory (DSmT) framework.