Angularjs updated value not updating ui-knob (chart)

[Tusharbalar]

Hello here is my html

<ui-knob id="mainKnob" value="value" options="options1"></ui-knob>

and js

.controller('AwardCtrl', function ($scope, getMembership){
  $scope.value = 10;

// called service
  getMembership.getMembership(userid).then(function(data) { 
       $scope.data = data; 
       $scope.value = parseInt(data.membership);
  });

  $scope.options1 = {
                animate : { enabled: true, duration: 1500, ease: 'bounce' },
                readOnly: true,
                size: 260,
                max: 31,
                subText: {
                    enabled: true,
                    text: 'DAYS LEFT',
                    color: '#f2f2f2;',
                    font: 'auto'
                },
                trackWidth: 55,
                barWidth: 30,
                trackColor: '#e6e6e6',
                barColor: '#81d8cf',
                dynamicOptions: true
            } 
})

But my knob is not updating after $scope.value has changed.