Matlab's BERtool and Theoretical curves for M-FSK

I am looking at the theoretical performance of orthogonal M-FSK (received
noncoherently) using bertool. The documentation says that it uses Equation
8.66 of Simon and Alouini's "Digital Communication over Fading Channels".
This equation can also be shown to be identical to Eqn 3.123 of Sklar's book
on Digital Communications and the adjoining Fig. 3.34. But bertool's graph
has about a 0.5dB worse performance compared to Sklar's figure for 16-FSK
(M, k = 4). 2-FSK appears to work fine.

Does anyone know if bertool uses an approximation or has anyone seen this
impact? Since this is just plotting an equation, there shouldn't be a 0.5dB
gap.

thanks for your help Start a New Thread