Trouble modifying post metakey value from frontend

Hi, I am trying to use a radio form to modify a custom metakey value for posts. The posts wont have the metakey assigned at first, so I will use update_post_meta for its fallback capability to add_post_meta.. but I am having trouble with something simple!
Anyone see whats wrong? my code gets the value correctly, but doesnt update the metakey on submit via button or with my fancy onclicks…

//Function to create radio buttons to change post metakey tentativeastatus
function display_tentative_approval_buttons() {
	    Global $post;
	$tentativeastatus = get_post_meta($post->ID, 'tentativeastatus', true);
	//check if pre-approved
	if ($tentativeastatus == "pre-approved") { $tentativeastatusp == "checked"; }
	//check if waitlisted
	if ($tentativeastatus == "waitlisted") { $tentativeastatusw == "checked"; }
	//check if denied
	if ($tentativeastatus == "denied") { $tentativeastatusd == "checked"; }
	//display current status
	echo '<small><u>Currently: ' . $tentativeastatus . '</u></small><hr />';
	//start the form
	echo '<form method="post" action="">' . wp_nonce_field('update_wcepsa_postmeta','wcepsa_inventory') . '
<input type="radio" name="tentativeastatus" value="pre-approved" onClick="submit();" ' . $tentativeastatusp . ' /> Pre-Approved<br />
<input type="radio" name="tentativeastatus" value="waitlisted" onClick="submit();" ' . $tentativeastatusw . ' /> Waitlisted<br />
<input type="radio" name="tentativeastatus" value="denied" onClick="submit();" ' . $tentativeastatusd . ' /> Denied <br />
<small>Click to Modify</small>
</form>';
}

//change tentative post status
if ( isset( $_POST['wcepsa_inventory'] ) && wp_verify_nonce($_POST['wcepsa_inventory'],'update_wcepsa_postmeta') )
    { //if nonce check succeeds.
        global $post;
        $postid = $post->ID;
        $data = $_POST['tentativeastatus'];
        update_post_meta($postid,'tentativeastatus',$data);
    }

anyone see why it wont save?