ASP.NET change AD password - asp.net

Question

I know this is ugly and I know I should have it in try blocks I've just been tinkering trying to get it to work. I'm missing something here and I would really appreciate some help figuring it out. All I'm trying to do is to create a page with a text box for the login name as well as one for the old password and two for the new password. To add more information the error I'm getting now is
Unknown name. (Exception from HRESULT: 0x80020006 (DISP_E_UNKNOWNNAME))
when i try to invoke the ChangePassword
Dim userid As String
Dim password As String
Dim login As String
Dim check As String
login = txtLogin.Text
userid = txtLogin.Text
password = txtOldPass.Text
Dim entry As DirectoryEntry = New DirectoryEntry("LDAP://OU=PaidUsers,DC=LOCAL,DC=bb", "LOCAL\" & userid, password)
Dim obj As Object = entry.NativeObject
Dim search As DirectorySearcher = New DirectorySearcher(entry)
search.SearchScope = SearchScope.Subtree
search.Filter = "(SAMAccountName=" & login & ")"
Dim result As SearchResult = search.FindOne()
check = CType(result.Properties("sAMAccountName")(0), String)
If check = login Then
If txtNewPass.Text = txtNewPass2.Text Then
entry = result.GetDirectoryEntry()
entry.Username = "LOCAL\" & check
entry.Password = txtOldPass.Text
entry.AuthenticationType = AuthenticationTypes.Secure
entry.Options.Referral = ReferralChasingOption.All
entry.Invoke("ChangePassword", txtOldPass.Text, txtNewPass.Text)
entry.CommitChanges()
lblSuccess.Visible = True
Else
lblPasswdError.Visible = True
End If
Else
lblError.Visible = True
End If

Answer 1

The error that fixed it was the command to Get the directory entry before Invoking the "ChangePassword". What I didn't realize is once I go into the IF logic the entry directory entry didn't have the account I was trying to change, hence the UnknownName error. Calling the result of my initial query of LDAP found the user account and it worked like a charm. The working code is below;
lblError.Visible = False
lblSuccess.Visible = False
lblPasswdError.Visible = False
lblCatch.Visible = False
Dim userid As String
Dim password As String
Dim check As String
userid = txtLogin.Text
password = txtOldPass.Text
Dim entry As DirectoryEntry = New DirectoryEntry("LDAP://OU=PaidUsers,DC=LOCAL,DC=bb", "LOCAL\" & userid, password)
Try
Dim search As DirectorySearcher = New DirectorySearcher(entry)
search.SearchScope = SearchScope.Subtree
search.Filter = "(SAMAccountName=" & userid & ")"
Dim result As SearchResult = search.FindOne()
check = CType(result.Properties("sAMAccountName")(0), String)
If check <> Nothing Then
If check = userid Then
If txtNewPass.Text = txtNewPass2.Text Then
entry = result.GetDirectoryEntry()
entry.Username = "LOCAL\" & check
entry.Password = txtOldPass.Text
entry.AuthenticationType = AuthenticationTypes.Secure
entry.Options.Referral = ReferralChasingOption.All
entry.Invoke("ChangePassword", txtOldPass.Text, txtNewPass.Text)
entry.CommitChanges()
lblSuccess.Visible = True
Else
lblPasswdError.Visible = True
End If
Else
lblError.Visible = True
End If
Else
lblError.Visible = True
End If
Catch ex As Exception
lblCatch.Text = "Error message: " + ex.InnerException.Message
lblCatch.Visible = True
End Try