I started with gui Creation some days ago… and i dont know. Am i too stupid? 
First of all our little code snippet:
[xml]
<?xml version=“1.0” encoding=“UTF-8”?>
<nifty xmlns=“http://nifty-gui.sourceforge.net/nifty.xsd” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=“http://nifty-gui.sourceforge.net/nifty.xsd http://nifty-gui.sourceforge.net/nifty.xsd”>
<screen id=“start” controller=“de.lessvoid.nifty.examples.helloworld.HelloWorldStartScreen”>
<layer childLayout=“center” backgroundImage=“assets/Interface/MainMenu.jpeg”>
<panel backgroundColor="#000033" childLayout=“center” height=“100%” width=“100%” align=“center” valign=“center”>
<control id=“submitButton” type=“button” label=“submit!”>
</control>
</panel>
</layer>
</screen>
</nifty>
[/xml]
Seems valid to me… The image exists (and is in this folder only for testing purpose… i will move it later on 
)
Now… What is shown?
Nothing. A gray screen. I use the MonkeyPlatform to edit my GUI… I’m going crazy. I dont know, but I’m just too stupid for nifty. -.-"
Is there a error in my code… or better: Where is the error in my code? I’m quite new to nifty gui, so i beg for your pardon. >_<
@Momoko: I tried it without the “asset/” but it wouldnt work.
Maybe try the path without the “assets/” ?
Nothing. A gray screen.
well u try to see the result of ur xml-code by viewing in the "Design" tab? that didnt work for me since alpha-4 ^^
try it out within a simpleApplication! a bit annyoing...but there it should work
and "assets" should be deleted, like momoko-fan mentioned
for references :
http://hub.jmonkeyengine.org/groups/gui/forum/topic/get-nifty-screencontroller-to-work/
greetings
Terry
Well.
The “asset/” thing helped for sure. Thanks a lot. I would have searched a lot for THAT one… The other problems were solved by trial and error for 2 hours. 
But in the end it works. Thats all what counts.
Thanks a lot you two.
Oh great.
I think nifty tries to render me mad.
I got it to work and made some research concerning Controls, since i read the label-element was removed.
I found everything needed… so i thought.
[xml]<nifty xmlns=“http://nifty-gui.sourceforge.net/nifty.xsd”
xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=“http://nifty-gui.sourceforge.net/nifty.xsd
http://nifty-gui.sourceforge.net/nifty.xsd”>
<useStyles filename=“nifty-default-styles.xml” />
<useControls filename=“nifty-default-controls.xml” />[/xml]
Should handle the job, so i thought.
But i cant use controls it seems. I’m really freaking out. -.-"
[xml]<layer id=“Layer Left” backgroundImage=“Interface/MeinMenu.jpeg” childLayout=“center”>
<panel height=“100%” width=“100%” childLayout=“vertical” visibleToMouse=“true”>
<panel width=“27%” height=“100%” backgroundColor="#EEEEEE0A">
<control name=“label” text=“A Label” align=“left” textHAlign=“left” width=“130px” />
</panel>
</panel>
</layer>[/xml]
This is the essential part. It works as long as i delete the line
[xml] <control name=“label” text=“A Label” align=“left” textHAlign=“left” width=“130px” />[/xml]
Anyone any ideas? I’m getting rly tired of trial and error…
What does “not working” do exactly?
It shows a gray plane if i have the line, the correct way if i remove it.
If asked for i could upload screenshots, but its not much to see.
And you don’t get any sort of errors on the console output?
There was no error message until i changed some patterns in my testenviroment.
After that a error popped up which made very clear whats wrong;
The panel had no childLayout and that was, why the Niftyinterpreter aborted the interpreting.
To correct the Code all i had to do was to add a damned childLayout to the panel containing the control… God damn. Nowhere stood i would have to define a childLayout to every container. sigh
The easiest problems are the hardest to solve.
Thank you very much.
So much time wasted with to complex thoughts about such an error. i could bite my own … well. You know what i mean