VB.Net Answer Checker in Quiz - vb.net

Question

Please help me solve my problem in quiz checker. I have 4 choices which display in Radio Button. So my problem is after i check my radio button and submit it gives me score on the corresponding question but after i click the submit button again it adds another score on the same question. how can i prevent my checker to add another score on the same question?
Here is my code.
Public Sub Check()
If Check1.Text < 2 And Check2.Text < 2 And Check3.Text < 2 And Check4.Text < 2 Then
If CorrectAns.Text = CoAnsDB.Text Then
score = score + 1
Else
score = score + 0
End If
Else
score = score + 0
End If
End Sub
Private Sub BtnSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnSubmit.Click
Call Check()
'Call CheckerB()
'Call CheckerC()
'Call CheckerD()
MyScore.Text = score.ToString
BtnSubmit.Enabled = False
AnsA.Enabled = False
AnsB.Enabled = False
AnsC.Enabled = False
AnsD.Enabled = False
End Sub
Private Sub AnsA_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AnsA.CheckedChanged
CorrectAns.Text = "A"
If AnsA.Checked = True Then
Check1.Text = Check1.Text + 1
End If
BtnSubmit.Enabled = True
End Sub
Private Sub AnsD_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AnsD.CheckedChanged
CorrectAns.Text = "D"
If AnsB.Checked = True Then
Check4.Text = Check4.Text + 1
End If
BtnSubmit.Enabled = True
End Sub
Private Sub AnsC_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AnsC.CheckedChanged
CorrectAns.Text = "C"
If AnsC.Checked = True Then
Check3.Text = Check3.Text + 1
End If
BtnSubmit.Enabled = True
End Sub
Private Sub AnsB_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AnsB.CheckedChanged
CorrectAns.Text = "B"
If AnsB.Checked = True Then
Check2.Text = Check2.Text + 1
End If
BtnSubmit.Enabled = True
End Sub
Thank you.