Checkbox checked depening on value binded via data-ng-bind

I'm trying to edit a field and the checkbox should be checked or not checked depending on the existing data (1 for checked 0 for not checked)

<label class="icheck">
<input class="icheckbox_flat-blue" type="checkbox" data-ng-model="property[key]"  ng-true-value=1 ng-false-value=0 />
</label>

When i try realizing this with

ng-checked="property[key]==1" 

the value isn't set to 0 when i click on the already checked checkbox and it takes 3 clicks to change the checkbox value.