[ns] ns-2.1b8 compile error msg,need help

["s w" <nshowto@hotmail.com>]

Hi everyone,
I meet an error msg while compiling the ns-2.1b8a on win2000. The error msg 
is as below,
wireless-phy.h(75) : error C2555: 'WirelessPhy::node' : overriding virtual 
funct
ion differs from 'Phy::node' only by return type or calling convention
        phy.h(71) : see declaration of 'Phy'
NMAKE : fatal error U1077: 'cl' : return code '0x2'
Stop.

I opened the wirelessPhy.h and here is the line 75:
inline MobileNode* node(void) const { return (MobileNode*)node_; }

Are there someone meet the same problem before? How to correct this error 
msg?
Thanks.
tdd

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