Quadratic Equation Visual Basic 2010+ - visual-studio-2010

Question

I have to write a program which calculate quadratic equation and find its roots. The roots must be displayed via MsgBox-es, and the variables A, B and C must be entered via InputBox-es. For now I have written this, but it somehow doesn't work and I can't figure out why.
**I'm new to Visual Basic ..
Public Class Form1
Dim A As Integer
Dim B As Integer
Dim C As Integer
Dim Det As Double
Dim x1 As Double
Dim x2 As Double
Private Sub txtA_Click(sender As Object, e As EventArgs) Handles txtA.Click
txtA.Text = InputBox("Please, enter value of the variable A.", "Enter A")
End Sub
Private Sub txtB_Click(sender As Object, e As EventArgs) Handles txtB.Click
txtB.Text = InputBox("Please, enter value of the variable B.", "Enter B")
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub cmdCalculate_Click(sender As Object, e As EventArgs) Handles cmdCalculate.Click
A = Val(txtA.Text)
B = Val(txtB.Text)
C = Val(txtC.Text)
Det = B ^ 2 + 4 * A * C
If Det > 0 Then
x1 = (-B + Math.Sqrt(Det)) / (2 * A)
x2 = (-B - Math.Sqrt(Det)) / (2 * A)
MsgBox("The roots are " + x1 + " and " + x2 + " ! ", 64, "2 Roots")
ElseIf Det = 0 Then
x1 = -B / (2 * A)
MsgBox("The roots are " + x1 + " ! ", 64, "1 Double Root")
ElseIf Det < 0 Then
MsgBox("No roots ! ", 64, "No Roots")
End If
End Sub
Private Sub txtC_Click(sender As Object, e As EventArgs) Handles txtC.Click
txtC.Text = InputBox("Please, enter value of the variable C.", "Enter C")
End Sub
Private Sub cmdExit_Click(sender As Object, e As EventArgs) Handles cmdExit.Click
End
End Sub
Private Sub cmdClear_Click(sender As Object, e As EventArgs) Handles cmdClear.Click
txtA.Text = ""
txtB.Text = ""
txtC.Text = ""
End Sub
End Class
http://imgur.com/hIcDxFv <-- Screen view

Answer 1

Oh, the problem was just because the x1 and x2 must be in Str()..
If Det > 0 Then
x1 = (-B + Math.Sqrt(Det)) / (2 * A)
x2 = (-B - Math.Sqrt(Det)) / (2 * A)
MsgBox("The roots are " + Str(x1) + " and " + Str(x2) + " ! ", 64, "2 Roots")
ElseIf Det = 0 Then
x = -B / (2 * A)
MsgBox("The roots are " + Str(x) + " ! ", 64, "1 Double Root")