Adding new brush in RME 2.1

[Qbee]

Hello.
I wanted to add some brushes to my rme but i have a problem.
I added this :

<materialsextension name="custom" author="Qbee" description="" client="8.54;8.6">
<brush name="new swamp" type="ground" server_lookid="11548" z-order="11240">
<item id="11548" chance="2500"/>
<border align="outer" id="517"/>
</brush>

in extensions
and

	<border id="517">	
		<borderitem edge="n"   item="11551"/>
		<borderitem edge="e"   item="11550"/>
		<borderitem edge="s"   item="11549"/>
		<borderitem edge="w"   item="11552"/>
		<borderitem edge="cnw" item="11559"/>
		<borderitem edge="cne" item="11560"/>
		<borderitem edge="cse" item="11557"/>
		<borderitem edge="csw" item="11558"/>
		<borderitem edge="dnw" item="11554"/>
		<borderitem edge="dne" item="11553"/>
		<borderitem edge="dse" item="11555"/>
		<borderitem edge="dsw" item="11556"/>
	</border>

in borders.xml in 860 and 854 folders.

I only works with optional border tool.
my questions are:
1. why when I r-click on this tile there is no option "select groundbrush".
2. I'd also like to know how to add new brush into (for example) Terrain Palette > Cave.
3. What is z-border attribute?

 

[Qbee]

bump please help me