Error: Index and length must refer to a location within the string - vb.net

Question

Im getting the following exception on vb.net. I have trouble solving this error:
Error 5: Index and length must refer to a location within the string.Parameter name: length.
here is my code :
Private Sub attemptedNumbersNew2(ByVal date_start As DateTime, ByVal date_end As DateTime, ByVal port As String, ByVal team As String)
Dim con As New ADODB.Connection
Dim recordS As New ADODB.Recordset
Dim sql As String = "some query...."
Try
con.Open(connectStringA)
recordS.Open(sql, con)
If recordS.EOF Then
Else
Do While Not recordS.EOF
Dim temp As String
If name4number.Contains(lastAttempted) Then
temp = name4number.Item(lastAttempted)
Else
temp = lastAttempted
End If
If attemptedNames.Equals("NONE") Or attemptedNames.Equals("") Then
attemptedNames = temp
ElseIf Not temp.Equals("") Then
attemptedNames = attemptedNames & " - " & temp
End If
If agentsHashOffered.Contains(temp & "_" & team) Then
agentsHashOffered.Item(temp & "_" & team) = agentsHashOffered.Item(temp & "_" & team) + 1
Else
agentsHashOffered.Add(temp & "_" & team, 1)
End If
If recordS.Fields(2).Value >= oldDate Then
If answeringNumber.Equals("NONE") Then
answeringNumber = recordS.Fields(4).Value
If answeringNumber.Substring(0, 1).Equals("9") Then
answeringNumber = answeringNumber.Substring(1, 10)
End If
callDuration = -1
End If
disconnectionTime = recordS.Fields(3).Value
Else
End If
If attempted.Equals("NONE") Then
attempted = recordS.Fields(4).Value
If attempted.Substring(0, 1).Equals("9") Then
attempted = attempted.Substring(1, 10)
End If
attemptedCount = attemptedCount + 1
lastAttempted = attempted
Else
temp = recordS.Fields(4).Value
If temp.Substring(0, 1).Equals("9") Then
temp = temp.Substring(1, 10)
End If
attempted = attempted & " - " & temp
attemptedCount = attemptedCount + 1
lastAttempted = temp
End If
recordS.MoveNext()
Loop
End If
con.Close()
con = Nothing
recordS = Nothing
Catch ex As Exception
MsgBox("Error #" & Err.Number & ": " & Err.Description)
End Try
End Sub
It was working fine the other day, but suddenly I started getting this error.
any helps are welcome
THANK YOU in Advance