Bug 121352 The data set binding property cannot be retrieved in report preview layout
In report preview page, the datasource/dataset property binding lists cannot be retrieved. The dataset binding can not work correctly in layout preview because it's value cannot get from the binding list. But in the data set edit page, the binding value can be got. You can refer to the attachment.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
* Gets the definition of a user-defined property defined in this element or
	 * somewhere up the inheritance chain.
	 * <p>
	 * Part of: User-defined property system.
	 * 
	 * @param propName
	 *            The internal name of the user-defined property.
	 * @return The property definition, if found, null otherwise.
	 */
	public UserPropertyDefn getUserPropertyDefn( String propName )
	{
		DesignElement e = this;
		while ( e != null )
		{
			UserPropertyDefn p = e.getLocalUserPropertyDefn( propName );
			if ( p != null )
				return p;
			e = e.getExtendsElement( );
		}
		return null;
	}
	/**
	 * Gets the cached parent element. There will be no parent if either 1) the
	 * element does not extend from another user-defined element, or 2) the
	 * extends element is undefined.
	 * <p>
	 * Part of: Inheritance system.
	 * 
	 * @return parent element
	 */