system havn't audio streaming (no sound)on WIN7 PE,after load ADD

I builded a win7 PE used the WAIK for windows 7 base on the winpe.chm help document.

1: add the win7 pe package using the tool of "dism.exe"

2:add the hdaudio.inf ,hdaudiobus.inf offline driverinstallation using the tool of "dism.exe"

3:boot from UFD WIN7 PE ,and load all of the x:\windows\inf \*.inf using the drvload.exe ,register DLL files in the x:\windows\system32 using the regsvr32.exe in the "startnet.cmd"

4:Run "singen.exe /time:20000" in dos-command WIN7 PE , then NO audio output , It's same like the need to add some audio service such as (SVCHOST,)in win7 pe at first .

Could you help me on the audio function in WIN 7 PE( dos-command windows)