iam creating a simple login form and iam a noob in coding

there are no errors aside from showing this MSG after I login in "conversion from string "admin" type to double is invalid" am not even trying to convert a variable to a double so i don't know how to fix it. Here is the codes and what my table looks like.

    Private Sub login_Click(sender As Object, e As EventArgs) Handles login.Click
    Dim log As String
    Try
        If conn.State = ConnectionState.Closed Then
            conn.ConnectionString = "host=localhost; uid='root'; password=''; database= user_login"
            conn.Open()
            comm.Connection = conn

            log = "select * from user where username = '" & username.Text & "' and password ='" & password.Text & "'"

            comm.CommandText = log
            adap.SelectCommand = comm
            adap.Fill(dt, "user")
            If dt.Tables(0).Rows.Count > 0 Then
                MsgBox("You are now Logged in", MsgBoxStyle.Information, "Log in")
                If dt.Tables(0).Rows(0).Item(6).ToString = 6 Then
                    Dim frmMain As New MDIParent
                    frmMain.Show()
                Else
                    Dim frmMain As New MDIParent
                    frmMain.Show()
                End If
                Me.Hide()

            Else
                If username.Text = "" And password.Text = "" Then
                    MsgBox("User profile cannot be loaded No password or username detected", MsgBoxStyle.Critical, "Error!")
                Else
                    If username.Text = "" Then
                        MsgBox("No Username detected", MsgBoxStyle.Critical, "Error!")
                    Else
                        If password.Text = "" Then
                            MsgBox("No Password detected", MsgBoxStyle.Critical, "Error!")
                        Else
                            MsgBox("Log in failed the username or password is incorrect", MsgBoxStyle.Critical, "Error!")
                        End If
                    End If
                End If
            End If
        End If




    Catch ex As Exception
        MsgBox(ex.Message)
    Finally
        conn.Close()
    End Try
End Sub

End Class

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