Loading UMDF driver which calls DLL functions fails, when functions are defined as __cdecl

[sh192]

Hi,
I try to call DLL functions in a UMDF driver, but my driver does not
even load (error 31 in device manager) when the functions are defined
as __cdecl instead of __stdcall.
Why does this happen?
May I call __cdecl function from UMDF in general?
What else may I do to avoid this problems, than to build my DLL with
__stdcalls?

Thanks in advice

[sh192]

In the log file setupapi.log it says:
#-198 Command line processed: "C:\WINDOWS\system32\mmc.exe" C:\WINDOWS
\system32\devmgmt.msc /s
#I292 Changing device properties of "ROOT\DEVICE\0000".
#I292 Changing device properties of "ROOT\DEVICE\0000".
#I163 Device not started: Device has problem: 0x1f:
CM_PROB_FAILED_ADD.
#I294 DICS_ENABLE DICS_FLAG_GLOBAL: Enabling device globally.