problem in calculating and displaying price in textbox

[Prathap]

Hi all,
Check this code and please tell me a solution.I have 2 buttons (Pizza & pepsi),the price should display in textbox8 when i click on button, here the price had shown in Textbox8,but it is not getting added with next price when i click second button.

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
    con.ConnectionString = str
    TextBox8.Text = 0.0
    adp = New SqlDataAdapter("select Item,Price from Bill where Id = '1'", con)
    adp.Fill(ds)
    DataGridView1.DataSource = ds.Tables(0)
    TextBox8.Text = ds.Tables(0).Rows(0)("Price") + TextBox8.Text
    End Sub

[C CSR]

You put the first value in (the sum: x). You add a new value (y) to the old, but the old value isn't included in the new sum. It looks like:
init x = 0
x: old value
y: new value
x = x + y

Are you reinitializing x to 0 before you recalculate the new value? If y is showing up and x dissappears, then x has lost its value or it is being referenced correctly.

I'm just guessing.

[C CSR]

In the last part of THE LAST sentence, I mean maybe x ISN'T being referenced correctly (that is, if you're not reinitializing it to 0).