Problem With Getting Form Value

[robing]

I am having trouble getting data from a text input field element.
the element is called amount_$counter with $counter being the row of the table.
when i have made an input to the text field and submitted the onClick passes the table row to the javascript function, i then concatinate a string to be the same as the id of the element i want the input from.

i use the script below to get the input but the error i get is document.formPr oducts.nums.val ue; is null or not an object;

but when i use document.formPr oducts.object_6 .value;
in the alert i get what i have just inut into the field, so this tells me that "nums" is not correct but i can' for the life in me find the problem.

Please help!!!


<from name=f"ormProdu cts" method="get" action="">
<tr>
<td><input type='text' name='amount_$c ounter' id='amount_$cou nter' value='' size='3' >
</td></tr>
<tr>
<td>
<input name="btn_check out2" type="button" id="btn_checkou t2" value="" onClick=" pop_amount(<? echo $counter ?>);>
</td>
</tr>
</form>

<script>
function pop_amount(row) {
var amt='amount_';
var nums=amt+row;
//alert("element variable row " + row + "amt " + amt + " nums " + nums + "")

var vn = document.getEle mentById('nums' );
var eval=document.f ormProducts.num s.value;
//alert("element variable " + vn + " " + eval + " ")

}
</script>

[iam_clint]

Looks like nums is not a name or id of any of the input fields... get what i mean
if you wanted to get the value of document.formPr oducts.amount_$ counter.value