i am now doing the asp.net with javascript as client side script.
i have a script as below
<script language="javascript">
function recalStkBal(){
txtStkBal.value=parseFloat(txtOpenbal.value)-parseFloat(txtStkDed.value)
}
</script>

 and with the web control

<asp:textbox name="txtOpenBal">....
<asp:textbox name="txtStkDed">....
<asp:textbox name="txtStkBal">....

 and with code behind

private sub page_load(....)..
txtOpenBal.attribute.add("onBlur","recalStkBal()")

so what i expect is when the user lost focus from the txtOpenBal the "recalStkBal()" should raise and reset the txtStkBal.value to the new value.but i cannot get it so can or any one can help me up? thanks in advance.......

You can't set server controls value in javascript like this
txtStkBal.value=parseFloat(txtOpenbal.value)-parseFloat(txtStkDed.value)

You should do like this...
document.forms[0]['txtStkBal'].value=parseFloat(txtOpenbal.value)-parseFloat(txtStkDed.value)