Transferring Amount To Other Account - Number Format Exception

I'm doing this project in JSP.net, with html. and in one of the web pages, what I'm doing is that, a person is transferring an amount to someone else, and if the transfer amount is more than the account balance, then he cannot transfer. else, save details in a table.

Here's the code I've used

<%
String t1=request.getParameter("text1");
String t2=request.getParameter("text2");
java.util.Date date1 = new java.util.Date();
SimpleDateFormat ft = new SimpleDateFormat ("dd/MM/yyyy");
int tamt = Integer.parseInt(t2);
int bamt = 0;

[Code] .....

But when i enter the fields and click the submit button in the form, to save it in the table, i get the error:

"org.apache.jasper.JasperException: java.lang.NumberFormatException: null"

(I've attached a screen shot of the error) : NumberFormatException.bmp (750.98K)

What does this mean? how do i find the line in the code that has the error?