how to insert multiple values to lookup field in Sharepoint list?

Question

I have Assignee field which accepts multiple values and its lookup column but whenever i try to post multiple values I am getting the below error

"Cannot convert a primitive value to the expected type 'Edm.Int32'. See the inner exception for more details."

var x=document.getElementById("AU").value
     $scope.formData.AssigneeId={}
     $scope.formData.AssigneeId.results=[]; 

     x=x.split(';')
     for(var i=0;i<x.length;i++){
        // var user=[]
        // user.push([parseInt(x[i])])
        // var z=parseInt(x[i])
    $scope.formData.AssigneeId.results.push(parseInt(x[i]))
         }