JURI::isInternal

[travisapple]

JURI::isInternal returns FALSE when the url is something like "/index.php/foo" and so $flink is returning FALSE for actual internal pages. You need something like

$flink = $menuItem->flink;
if( substr($flink,0,1) == '/' ) {
    $flink = substr($flink,1);
}
    $isInternal = JURI::isInternal($flink);