Radio Button Troubles

I would like a radio button selected by default when the page loads
and then keep either the original selection or the new selection when the
page reloads.  I tried using the keyword CHECKED within the Html tag but it
always selcted that value.  I added the following script to hold the value
after it was selected before the radio buttons were defined:

if (l1_SCRN01$SELPO.value == 'X') document.SCREEN.POPUR[0].checked = true;
if (l1_SCRN01$SELPRT.value == 'X') document.SCREEN.POPUR[1].checked = true;

After adding this the page did not behave as it was supposed to.  Normally I
would choose between an option and then hit Enter.  It would then search by
the appropriate selection criteria.  Adding those above statements changed
that.  When I take them out it works fine but I have to always select a
radio button.  I used the following code below when setting up radio buttons
within my application.  Thanks.

Mark Giordano

<SPAN class="wf_default wf_field">
<INPUT  TYPE="radio" NAME="POPUR"
onClick="set_trans_opt(l1_SCRN01$SELPO,l1_SCRN01$SELPRT,'X', ' ');" >PO #
<INPUT  TYPE="radio" NAME="POPUR"
onClick="set_trans_opt(l1_SCRN01$SELPO,l1_SCRN01$SELPRT,' ','X');">Part No.
</SPAN>

The function set_trans_opt is as follows:

function set_trans_opt(field1,field2,value1,value2){

field1.value = value1;

field2.value = value2;

setFocusAndValue(field1,value1)

setFocusAndValue(field2,value2)}