[Solved] StgIsStorageFile always returns 1 in ASP.Net

How can we identify if the file is a storage file or not. Both are of same .doc format.

I have a code to find if file is a storage file or not with the help of ole32.dll.

Below is my code.

[DllImport("ole32.dll", CharSet = CharSet.Unicode)]
public static extern int StgIsStorageFile(string pwcsName);

 Calling in below manner:

StgIsStorageFile(this.filePath) != 0)
    return false;

Now there is a file uploaded by the client in .doc format.

For some reason, this file always returns 1 means it is not a StorageFile. 

When I manually created .doc file with the same content it works fine.