Angular: then execute before http call complete

When I call addCategory, it suppose to add my new category and then call _initAdminController() to go back to my main page and refresh the data there. But what is happening is getcourselist and getsubjectlist in initAdminController are somehow running first and then addCategory runs last. Do you know what can cause this? Am I using then correctly?

function _initAdminController() {
    $scope.pageIndex = "adminTab";
    console.log("reloading data");

    $http({
        method : 'GET',
        url : 'http://testserver.com:8082/getSubjectListService'
    }).then(function successCallback(response) {
        $scope.updatedSubjects = response.data;
    }, function errorCallback(response) {
        console.log(response.statusText);
    });

    $http({
        method : 'GET',
        url : 'http://testserver.hughes.com:8082/getCategoryListService'
    }).then(function successCallback(response) {
        $scope.categories = response.data;
    }, function errorCallback(response) {
        console.log(response.statusText);
    });
}

$scope.addCategory= function(){

    var name = $scope.addCategoryData.name;
    var desc = $scope.addCategoryData.description;

    $http({
        method : 'POST',
        url : 'http://testserver.com:8082/addCategoryService',
        withCredentials: true,
        cache: true,
        headers : { 'Content-Type': 'application/json' },
        data : {
            name: name,
            description: desc
        }
    }).then(_initAdminController(), function errorCallback(response) {
        console.log(response.statusText);
    });
}

Also when I use then for http get, that case is working correctly. The http get finishes first and then my scope variable get updated. And lastly before I tried the following code and in that case, successCallback doesn't run at all. So does this mean then only works for GET?

$http({
    method : 'POST',
    url : 'http://testserver.com:8082/addCategoryService',
    withCredentials: true,
    cache: true,
    headers : { 
        'Content-Type': 'application/json' 
    },
    data : {
        name: name,
        description: desc
    }
}).then(
    function successCallback(response) {
        _initAdminController()
    }, 
    function errorCallback(response) {
        console.log(response.statusText);
    }
);