con.Open()
cmd.CommandText = "select * from userid where 用户名= '" + useridtxt.Text + "' "
cmd.Connection = con
da.SelectCommand = cmd
da.Fill(ds, "userid")
con.Close()

If ds.Tables("userid").Rows(0).Item(1) = passwordtxt.Text Then
newform1.ShowDialog()
Me.Hide()
Else
Exit Sub
End If
我这样写有什么错误吗？？功能就是不能实现

Dim con As New SqlConnection("data source=.; database=test; uid=sa; password=")
Dim cmd As New SqlCommand
Dim da As New SqlDataAdapter
Dim ds As New DataSet
con.Open()
cmd.CommandText = "select * from usertable where 用户名= '" + useridtxt.Text + "' "
cmd.Connection = con
da.SelectCommand = cmd
da.Fill(ds, "userid")
con.Close()

If ds.Tables("userid").Rows(0).Item(1) = passwordtxt.Text Then
'newform1.ShowDialog()
'Me.Hide()
Label1.Text = "成功"
Else
Exit Sub
End If