Need help with do loop until

[Pauwl]

ok here goes. I have the following code for checking if a user exists in a NT domain:

if NetUserGetInfo(bServer(0), bUsername(0), 3, lpBuf) = ERR_Success) then
        Dim lpBuf As Long
        Dim ui3 As USER_INFO_3
        Dim bServer() As Byte, bUsername() As Byte
        bServer = "\\tempsrv" & vbNullChar
        bUsername = username & vbNullChar
        Call MoveMemory(ui3, ByVal lpBuf, Len(ui3))
msgbox "username " & username & " already exists"
else
blabla create user
end if

and the following code for putting a follownumber at the end of the username:

username = Left(username, Len(username) - 1) & Right(username, 1) + 1

how can i put this in a loop that if username1 and username2 already exist it creates a username username3 for example???

I hope you know what i mean

[Pauwl]

no 1???
I'm pretty sure there are a lot of "loop" cracks over here

[Pauwl]

still not figured out yet

can anyone send me in the right direction?