NDIS installation issue on Win2K

Hello Experts,
We have a problem, when we try to install our NDIS intermediate driver on Win2K programmatically. The manual installation works fine, but our install program fails with the following error: “The INF or the device information set or element does not match the specified install class.” Error code: 0x800f0201 SPAPI_E_CLASS_MISMATCH. The failing class/function is:
INetCfgClassSetup *pncClassSetup = NULL;
hr = pncClassSetup->Install(szComponentId, &OboToken, 0, 0, NULL, NULL, &pncc);
The install program works fine on XP, 2003 and Vista.
Any help would be appreciated!