Impersonate a user on a PC that's in a workgroup connected to my domain

See more:

.NET3.5

C#

.NET

Hello,

I have a c# application which impersonate other users on my domain using their credentials(User name and password).

It's working as expected. However an attempt to impersonate a User on a PC in a certain Workgroup that is connected to my domain would give me an error:

Login Failure: unknown user name or bad password.

This is the method that does the actual impersonation:

private void ImpersonateValidUser(
    string userName,
    string domain,
    string password) {
    WindowsIdentity tempWindowsIdentity = null;
    IntPtr token = IntPtr.Zero;
    IntPtr tokenDuplicate = IntPtr.Zero;
    try {
        if (RevertToSelf()) {

            if (LogonUser(
                userName,
                domain,
                password,
                LOGON32_LOGON_INTERACTIVE,
                LOGON32_PROVIDER_DEFAULT,
                ref token) != 0) {
                if (DuplicateToken(token, 2, ref tokenDuplicate) != 0) {
                    tempWindowsIdentity = new WindowsIdentity(tokenDuplicate);
                    impersonationContext = tempWindowsIdentity.Impersonate();
                }
                else {
                    throw new Win32Exception(Marshal.GetLastWin32Error());
                }
            }
            else {
                throw new Win32Exception(Marshal.GetLastWin32Error());
            }
        }
        else {
            throw new Win32Exception(Marshal.GetLastWin32Error());
        }
    }
    finally {
        if (token != IntPtr.Zero) {
            CloseHandle(token);
        }
        if (tokenDuplicate != IntPtr.Zero) {
            CloseHandle(tokenDuplicate);
        }
    }
}

And as I said, this works perfectly if I try to impersonate a user on my domain. What I want is to be able to impersonate a User on a PC that's in a workgroup connected to my domain.

Any idea how to resolve this issue?

Thank you