Help with isometric z order

Hi, i'm new to Construct and have recently started a game.

I eventually intend to make an action adventure game with an isometric perspective, inventory, dialogue and a working combat system. Although i'll deal with those challenges when I come to them!

So far I have several sprites (player, npc and some scenery) and working collision - although I forsee future problems with the way i've done it.

But when it comes to implementing a way to get the sprites overlapping correctly i'm completely stuck. I've tried to create some on overlapping events so that the player sprite is placed behind terrain when overlapping and behind npcs when overlapping. I works for the terrain but not the npc.

Am I using else conditions incorrectly?

I'm aware this is likely a common newb problem, but please take a look - any help or advice would be much appreciated!

http://www.mediafire.com/?ljy4yyv2qwe7w2p

Isometric sorting example:

Thank you - I'm embarassed I didn't find it before I posted!

Although I must admit I don't understand how it works - it will take me some time to get to grips with arrays.

For now i've just used an event that sends each object in the terrain family to the front based on a z variable which is determined by its y position. It was used in Scidave's Adventure tutorial. It seems to work fine at the moment and will likely suffice as long as I don't do complex elevation stuff. Fine for a simple game perhaps, but i'll have to learn more if I want to do anything more complicated.