REST call is_public_list does not work

I tested the rest call through the wle,
rest call I perform : /asset?limit=200&is_public_list=true&order_by=videotimestamp&order_direction=desc
response ( small part )
<item id="4">
<asset_id>9sIt4Z4AqsQSltb8VDvyXBJv</asset_id>
<app_id>3</app_id>
<provider_id></provider_id>
<owner_id>krkeppen</owner_id>
<group_id>E87</group_id>
<videotimestamp>2010-03-23 15:32:26</videotimestamp>
<videotimestampmodified>2010-03-23 15:32:45</videotimestampmodified>
<play_restriction_start></play_restriction_start>
<play_restriction_end></play_restriction_end>
<locked>FALSE</locked>
<reference_id></reference_id>
<isprivate>TRUE</isprivate>
<mediafile_duration>00:06:16.84</mediafile_duration>
<mediafile_container_type>mov;mp4;m4a;3gp;3g2;mj2</mediafile_container_type>
<is_unappropiate>FALSE</is_unappropiate>
<is_external>FALSE</is_external>
<viewed>376</viewed>
<played>4</played>
<is_empty_asset>FALSE</is_empty_asset>
<is_protected>FALSE</is_protected>

Don't you use is_app_admin=TRUE parameter?
You can check it at the end of your response->header->request_uri.
WLE may automatically put this in the uri. And when you are app admin, you can see the isprivate=TRUE content too.