you are using <div my-date-picker ng-model="date"> datepicker dirctive
that means your going to replace inside of this div, by the template in the directive so your {{ Date }} is no longer there its replaced by the template.
if u put {{ Date }} outside of the div it will work
and note that model is not date it should be Date coz the model name of the input is Date check the directive template
template: '<input class="dateInput" is-open="openthis.isOpened" type="text" datepicker-popup="dd-MM-yyyy" ng-model="Date" ng-required="true" />'
working plunker
OR you can add {{ Date }} to the directive template
template: '<input class="dateInput" is-open="openthis.isOpened" type="text" datepicker-popup="dd-MM-yyyy" ng-model="Date" ng-required="true" />' +
'<span ng-click="open($event)" class="glyphicon glyphicon-calendar calImage"></span>'+
'<h2>{{ Date }}</h2>',