The emission of a scalar with low energy ω, from a D (4< D< 8 ) dimensional black hole with n charges is studied in both string and semiclassical calculations. In the lowest order in ω, the weak coupling string and semiclassical calculations agree provided that the Bekenstein--Hawking formula is valid and the effective central charge c_eff=6 for any D. When the next order in ω is considered however, there is no agreement between the two schemes unless D=5, n=3 or D=4, n=4.