Redmine

I am using the REST API in PHP. I have been successful in creating projects, but unsuccessful in creating subprojects.

I used the "parent_id" parameter as shown here: #7404

Here is the code I am using:

$rm_project = new Redmine_Project(array(
'name' => 'Project', 
'identifier' => 'project1',
'description' => 'desc'
));
$rm_project->save();

$rm_sub_project = new Redmine_Project(array(
'name' => 'Sub Project', 
'parent_id' => $rm_project->id,
'identifier' => 'subproject1',
'description' => 'testing'
));