Greetings,

I'm trying to join a computer to a domain by using NetJoinDomain from
netapi32.dll. I found the signature on pinvoke.net, but am having difficulty
getting it to work. I was hoping someone could check my code to make sure
that I am doing it right -- (this is one of my first forays into interop).

       [DllImport("netapi32.dll", CharSet=CharSet.Unicode)]
       public static extern int NetJoinDomain(
           string lpServer,
           string lpDomain,
           string lpAccountOU,
           string lpAccount,
           string lpPassword,
           int fJoinOptions);

       [Flags]
       public enum JoinOptions
       {
           NETSETUP_JOIN_DOMAIN = 0x00000001,
           NETSETUP_ACCT_CREATE = 0x00000002,
           NETSETUP_ACCT_DELETE = 0x00000004,
           NETSETUP_WIN9X_UPGRADE = 0x00000010,
           NETSETUP_DOMAIN_JOIN_IF_JOINED = 0x00000020,
           NETSETUP_JOIN_UNSECURE = 0x00000040,
           NETSETUP_MACHINE_PWD_PASSED = 0x00000080,
           NETSETUP_DEFER_SPN_SET = 0x10000000
       }

I am calling the NetJoinDomain method like so:

int retval = NetJoinDomain(null,
"Domain",
"OU...",
"Domain\DCAdmin",
"DCPassword",
(int) (JoinOptions.NETSETUP_JOIN_DOMAIN | JoinOptions.NETSETUP_ACCT_CREATE));

I get a return code of 2691 - NERR_SetupAlreadyJoined . Now, the machine is
already a member of an NT domain, which I want to move to a new AD domain, so
I tried adding the option of NETSETUP_DOMAIN_JOIN_IF_JOINED . However, this
results in a 1355 - ERROR_NO_SUCH_DOMAIN . I've tried other option
combinations, but without success.

Now, I know the domain exists, and I can Join the new domain successfully
using NETDOM.exe, so I'm wondering what else I can be doing wrong. I was
thinking maybe I am passing in the join options parameter incorrectly, but I
am not sure of another way to do it. Any ideas?

Thanks,
Peter