about BDA Tuner for directx9.0

DirectX9 Winxp ;

i use GraphEdit to Test BDA Tuner Drivers,i got this
result whatever the Network Provider filter is (dvb_c or
dvb_t ot dvb_s):

all the node’s properties of the
KSPROPSETID_BdaDigitalDemodulator set in Tuner Driver have
been registered;

when i fire all properties of this set by running
graphedit, the KSPROPERTY_BDA_MODULATION_TYPE property is
not called, but other properties:
KSPROPERTY_BDA_INNER_FEC_TYPE ,
KSPROPERTY_BDA_SYMBOL_RATE … can be called;


DEBUG RESULT:
i use softice to find:
in Msdvbnp!CMPEG2Receiver::Locate() function no call
bdaPlgin!CBdaDigitalDemodulator::put_ModulationType(…);

…this why?

.