The WP New footer command creates and returns the footer associated to the section or subsection defined by the wpSection parameter. 
If a footer element is already defined for the section or subsection, an undefined object is returned and an error is generated. 
You want to create a footer for the left pages of a section:
  var $section ;$subsection ;$footer : Object
  
 $section:=WP Get section(wpDoc;1)
  
 $subsection:=WP Get subsection($section;wk left page)
 
  
 If($subsection#Null)
    $footer:=WP New footer($subsection)
 End if