javascript calculation

I'm trying to have javascript calculate an amount when the user inputs a number.

           <script type="text/JavaScript">
                function Calculate()
                 {
                     var TextBox2 = parseInt(document.getElementById('<%= numJazzPresident.ClientID%>').value);
                     var TextBox3 = parseInt(document.getElementById('<%= numWinePaint.ClientID%>').value);
                     var TextBox4 = parseInt(document.getElementById('<%= numVariety.ClientID%>').value);
 
                   if (TextBox2 == " ") {        var jazzDollar = 0;           }
                   else {                       jazzDollar = (parseInt(TextBox2) * 20);            }

                   if (TextBox3 == " ") {         var wineDollar = 0;             }
                   else {                        wineDollar = (parseInt(TextBox3) * 20);           }

                   if (TextBox4 == " ") {           var varietyDollar = 0;              }
                   else {                       varietyDollar = (parseInt(TextBox4) * 10);         }

                   document.getElementById('<%= TotalAmount.ClientID%>').value = alumniDollar + jazzDollar + wineDollar;
    }         </script>


html code

   <asp:TextBox ID="numJazzPresident"  onchange="return Calculate(this)"  runat="server" Width="32px" ></asp:TextBox>
--------------------------------------------
the "totalAmount"   textbox never gets updated
bcrooksAsked:
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Julian HansenCommented:
Where is alumniDollar defined?
document.getElementById('<%= TotalAmount.ClientID%>').value = alumniDollar + jazzDollar + wineDollar;

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This is throwing an error which is why your text box is not being updated

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Russ SuterSenior Software DeveloperCommented:
There are a few things wrong with this code. You have undeclared variables and other variables that are declared but go out of scope before they are used in the final line of code.
SteHCommented:
Do the "empty" text boxes really contain a single space? Otherwise the comparison should be
if (TextBox4 == "") 

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bcrooksAuthor Commented:
Thanks - its always the simple things
Julian HansenCommented:
You are welcome
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