Evaluation Error in QtXmlPatterns, variable bindings

declare variable $global1 := "";                       
declare variable $global2 := "";                       

declare function local:f1 ( $a1  , $a2   ) as xs:string
{                                                      
  $a2
};

declare function local:f2 ( $a3   ) as xs:string
{
  ""
};

let $da :=
<d1>
  <table name="one"/>
  <table name="two"/>
</d1>

let $e1 :=
  element e1 {
    for $i in $da/table
    let $var1 := $i/@name
    return
      element  e2
        {
          attribute atr1 { local:f1("", $var1) },
          attribute atr2 { local:f2($global2)  }
        }
 }
 let $result :=  for $i in $e1/e2/@atr1 return string($i)
 let $notused1 := $global2

return
 $result, "&#10;"