xtext error: The first rule must be a parser rule.

I 've got an error on creating my own Terminals in Xtext:

grammar de.lastit.webapp.WebAppDsl with org.eclipse.xtext.common.Terminals

generate webAppDsl "http://www.lastit.de/webapp/WebAppDsl"

terminal ARRAY: '[' ... ']';

Model :

(elements+=Element)*;

The Solution is simple: own "terminal" rules must be at the end of the file:

grammar de.lastit.webapp.WebAppDsl with org.eclipse.xtext.common.Terminals

generate webAppDsl "http://www.lastit.de/webapp/WebAppDsl"

Model :

(elements+=Element)*; 

[...]

terminal ARRAY: '[' ... ']';

Keywords: MDSD,Eclipse,EMF,Xtext,terminal,error,oAW