Button Not Calculating Adverage Marks In Array

I have a project where I am to enter a name and a test mark into two separate text boxes and then select the button to store the information into the arrays, one array for names and another for marks and then you can click the calculate adverage mark button and a label should calculate the adverage mark but I cannot get the marks to be added and then divided by the number of entered marks. Such as: you enter in a name and a mark of 75, and then another name and a mark of 50 and then another final name and mark of 25. I have been trying to get it to add up the marks of 75, 50, 25 and then divide it by 3 the number of marks in the array, but it wont and I cant get it to add the marks as a integer no matter what I seem to do.

Here is my code:
Public Class frmAdverageTestMarkCalculator
Dim ClosingMsg As String
Dim Closingtitle As String
Dim SureAboutClosing As MsgBoxStyle
Dim Closingresponse As MsgBoxResult
[Code] .....