Good afternoon folks,

I stumbled on this forum during class and thought this would be the best place to get advice (my instructor was very vague and I didn't understand my questions).

The message box says that, "Number cannot be a letter and must be positive".

I have no issue with a negative number setting off the message box, but whenever I put a letter in the text box, no message pops up. I'll post my whole code for situation awareness, but the code that I'm having trouble will be at the bottom.

Code:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btbcalculate.Click
     ' Declare variables.
        Dim intRunner1time As Integer
        Dim intRunner2time As Integer
        Dim intRunner3time As Integer
        Dim strRunner1 As String = String.Empty
        Dim strRunner2 As String = String.Empty
        Dim strRunner3 As String = String.Empty

        ' Get input 
        Try
            intRunner1time = CInt(txttime1.Text)
            intRunner2time = CInt(txttime2.Text)
            intRunner3time = CInt(txttime3.Text)
            strRunner1 = txtRunner1.Text
            strRunner2 = txtRunner2.Text
            strRunner3 = txtRunner3.Text


                'Display race results
                If intRunner1time < intRunner2time And intRunner1time < intRunner3time And intRunner2time < intRunner3time Then
                    lblfirst.Text = strRunner1
                    lblsecond.Text = strRunner2
                    lblthird.Text = strRunner3
                ElseIf intRunner1time < intRunner2time And intRunner1time < intRunner3time And intRunner3time < intRunner2time Then
                    lblfirst.Text = strRunner1
                    lblsecond.Text = strRunner3
                    lblthird.Text = strRunner2
                ElseIf intRunner2time < intRunner1time And intRunner2time < intRunner3time And intRunner1time < intRunner3time Then
                    lblfirst.Text = strRunner2
                    lblsecond.Text = strRunner1
                    lblthird.Text = strRunner3
                ElseIf intRunner2time < intRunner1time And intRunner2time < intRunner3time And intRunner3time < intRunner1time Then
                    lblfirst.Text = strRunner2
                    lblsecond.Text = strRunner3
                    lblthird.Text = strRunner1
                ElseIf intRunner3time < intRunner1time And intRunner3time < intRunner2time And intRunner1time < intRunner2time Then
                    lblfirst.Text = strRunner3
                    lblsecond.Text = strRunner1
                    lblthird.Text = strRunner2
                ElseIf intRunner3time < intRunner1time And intRunner3time < intRunner2time And intRunner2time < intRunner1time Then
                    lblfirst.Text = strRunner3
                    lblsecond.Text = strRunner2
                lblthird.Text = strRunner1
            End If

            'display name errors
            If txtrunner1.Text = String.Empty Then
                MessageBox.Show("Please enter a name")
            ElseIf txtrunner2.Text = String.Empty Then
                MessageBox.Show("Please enter a name")
            ElseIf txtrunner3.Text = String.Empty Then
                MessageBox.Show("Please enter a name")
            End If

            'Display negative number and letter error
            If Integer.TryParse(txttime1.Text, intRunner1time) And IsNumeric(intRunner1time) And intRunner1time < 0 Then
                MessageBox.Show("Number cannot be a letter and must be positve")
            ElseIf Integer.TryParse(txttime2.Text, intRunner2time) And IsNumeric(intRunner2time) And intRunner2time < 0 Then
                MessageBox.Show("Number cannot be a letter and must be positve")
            ElseIf Integer.TryParse(txttime3.Text, intRunner3time) And IsNumeric(intRunner3time) And intRunner3time < 0 Then
                MessageBox.Show("Number cannot be a letter and must be positve")
            End If
        Catch ex As Exception
        End Try
    End Sub