Vista - Error to get IThumbnailProvider object, who can help me??

When I used IShellItem::BindToHandler method to get IThumbnailProvider
object, I got an error:
System.AccessViolationException: Attempted to read or write protected
memory. This is often an indication that other memory is corrupt.

My test environment: vs2005, c#, Windows Vista
My code is:
IShellItem pFileItem;
Guid itemRiid = new Guid("43826d1e-e718-42ee-bc55-a1e261c37bfe");
SHCreateItemFromParsingName(file,
IntPtr.Zero,
ref itemRiid,
out pFileItem);
if (pFileItem != null)
{
IThumbnailProvider pThumbProvider;
Guid riid = new Guid("66742402-F9B9-11D1-A202-0000F81FEDEE");
Guid bhid = new Guid("7b2e650a-8e20-4f4a-b09e-6597afc72fb0");
pFileItem.BindToObject(IntPtr.Zero, bhid, ref riid, out
pThumbProvider);
}