Failed to access to PGDB

Tried to access to a PGDB using the code below:
public IFeatureClass GetFCfromPGDB(string fPath, string fName) {
IWorkspaceFactory2 workspaceFactory = new ESRI.ArcGIS.DataSourcesGDB.AccessWorkspaceFactoryClass();
ESRI.ArcGIS.Geodatabase.IWorkspace pWS = workspaceFactory.OpenFromFile(fPath, 0);
IFeatureClass fc = GetFeatureClass(pWS, fName);
return fc;
}
Got COMException: Retrieving the COM class factory for component with CLSID {DD48C96A-D92A-11D1-AA81-00C04FA33A15} failed due to the following error: 80040111 ClassFactory cannot supply requested class (Exception from HRESULT: 0x80040111 (CLASS_E_CLASSNOTAVAILABLE)).
How to handle this problem? Thanks.