Cant install Templates of an plugin

Hi folks,

on mt4 ive made some plugins wich install needed indexes by pushing the "Install Template" button in the plugin setting area.

this feature doesnt work fine in MT5 and i cant localte realy good where the problem is.

i only see the lettering link "Install...." the image and the function is missing.

sample, in my yaml im using in mt4 this here:

# application handler
applications:
cms:
methods:
function_name: $PluginName::PluginName::App::CMS::function_name
function_install_templates: $PluginName::PluginName::App::CMS::install_templates

The installer subroutine does not do any wild thing, only this here:

sub install_templates {
my $app = shift;
my $installer;
eval { $installer = MT::Plugin::TemplateInstaller->instance; };
if ($@) {
$app->build_page('get_template_installer.tmpl');
} else {
$app->forward('install_blog_templates',@_);
}
}

my main question, is it possible that this feature/function... on mt5 not realy supported?
whats my mistake?

the only error i become is about my firebug: NS_ERROR_DOM_SECURITY_ERR. but i dont mean this is realy the reason...