angular js ui-select option repeat not working for object array

I am using Angular ui-select. My model & ui-select option array are different. While changing value its not updated and not displaying options. I am storing the selected object Id in "pmpo", I want to show the selected object from the pmptnk object array when loading. But is not working. Some one tell what I am doing wrong.

My object from Model

  pmpo:877
  pmptnk:[0:
    632:{id: "632",  pid: "2993", ESID: "9154", lb1: "Undddd", lb2: "219"}
    877:{id: "877",  pid: "2993", ESID: "9154", lb1: "Pcddd", lb2: "29"}
    654:{id: "654",  pid: "2993", ESID: "9154", lb1: "kukuu", lb2: "246"}]

In view file

 <div ng-if="item.pmptnk.length > 0">
    <ui-select ng-model="item.pmpo" click-out-side="closeThis($event)">
    <ui-select-match placeholder="Select " search-placeholder="Filter Tanks" 
    uib-tooltip="{{item.pmpo > 0 ? $select.selected.lb1 : 'Select Tank'}}" tab-select="true">
         <span ng-bind="$select.selected.lb1"></span>
    </ui-select-match>
    <ui-select-choices repeat="obj.tid as obj in (item.pmptnk[item.pmpo])">
        <span ng-bind="obj.lb1"></span>
    </ui-select-choices>
    <ui-select-no-choice>
      No results matched "{{$select.search}}"
    </ui-select-no-choice>
    </ui-select>

</div>

I worked on your code.I tried it out in different way. Below is my code snippet:

<div ng-if="item.pmptnk.length > 0">
  <ui-select ng-model="item.selected" click-out-side="closeThis($event)">
    <ui-select-match
      placeholder="Select "
      search-placeholder="Filter Tanks"
      uib-tooltip="{{item.pmpo > 0 ? $select.selected.lb1 : 'Select Tank'}}"
      tab-select="true"
    >
      <span ng-bind="$select.selected.lb1"></span>
    </ui-select-match>
    <ui-select-choices repeat="obj.tid as obj in (item.pmptnk)">
      <span ng-bind="obj.lb1"></span>
    </ui-select-choices>
    <ui-select-no-choice>
      No results matched "{{$select.search}}"
    </ui-select-no-choice>
  </ui-select>
</div>

and i changed my model as below:

$scope.item = {};
$scope.item.pmpo = 877;
$scope.item.pmptnk = [
  { id: "632", pid: "2993", ESID: "9154", lb1: "Undddd", lb2: "219" },
  { id: "877", pid: "2993", ESID: "9154", lb1: "Pcddd", lb2: "29" },
  { id: "654", pid: "2993", ESID: "9154", lb1: "kukuu", lb2: "246" },
];
for (var i = 0; i < $scope.item.pmptnk.length; i++) {
  if ($scope.item.pmptnk[i].id == $scope.item.pmpo) {
    $scope.item.selected = $scope.item.pmptnk[i].tid;
    break;
  }
}

This worked fine for me.