Change menu per page with custom theme locations

Hello, I’m trying to make new functonality on my website. Theme is Responsive Theme by cyberchimps.

I was using header_menu location as defult, but now I need to upgrade my menu. I need to change menu to another on all school pages.
I have to use custom locations because I have two languages on my website (new menu for each language).

I’ve registered two custom theme locations with this code:

register_nav_menus( array(
	"school_menu" => "School Menu",
	"agency_menu" => "Agency Menu",
) );

I created menus and links from Admin > View > Menu for each location, and I’have inserted this code in header.php of my child theme:

<?php if ( is_page(54) || "54" == $post->post_parent ) {
// the page is "School", or the parent of the page is "School"
	wp_nav_menu( array(
		"container"       => "div",
		"container_class" => "main-nav",
		"fallback_cb"     => "responsive_fallback_menu",
		"theme_location"  => "school-menu"
	) );
} else {
	wp_nav_menu( array(
		"container"       => "div",
		"container_class" => "main-nav",
		"fallback_cb"     => "responsive_fallback_menu",
		"theme_location"  => "agency-menu"
	) );
} ?>

instead of default code:

<?php wp_nav_menu( array(
	"container"       => "div",
	"container_class" => "main-nav",
	"fallback_cb"     => "responsive_fallback_menu",
	"theme_location"  => "header-menu"
) ); ?>

After refreshing page there was no custom menu, only old header menu.
I found a field “Header menu” on Admin > View > Menu > Locations, where i selected nothing.

And after refreshig page again I’ve got all pages of my website in my menu and no menus from custom theme locations.

I think the problem is with ocerwriting theme locations configurations.
I hope you can help me to fix this. Thank you.

P.S. Sorry for my English – it’s not my native.