Because you don't understood what OG has mentioned :
Supposing that your code is basicly correct you should change minimum the following :
Dim total As DOUBLE = 0
For t As Integer = 0 To Datagrid2.Columns.Count - 1
total += cdbl(Datagrid2.Items(t).Cells(5).Text)
Next
Label14.Text = total.toString
- you can't add a Value inside a String
- if you want to have a total you should sum it ...