Link a Lead record to a Project record using logic hook

I have created a one-to-many relationship between Project and Lead records. (called 'project_leads_1' in Studio)

I would like it so that when a new Lead record is created that meets certain criteria (last name = '@Incoming Email Sales Lead'), the Lead record is linked to a specific Project Record ('Incoming Email Sales' Project).

However, it's not working.  What am I missing?

I'm using 'before_save' logic hook on the Leads module

.....

$rel_name = 'project_leads_1';  // name of the relationship in Studio

$incoming_sales_leads_proj = [hard coded ID];

$incoming_service_leads_proj = [hard coded ID];
if($bean->last_name == '@Incoming Email Sales Lead')
{
$bean->load_relationship($rel_name);
$bean->$rel_name->add($incoming_sales_leads_proj);

}
else if($bean->last_name == '@Incoming Email Service Lead')
{
 $bean->load_relationship($rel_name);
 $bean->$rel_name->add($incoming_service_leads_proj);
}

......

Sugar 13.0