Bug 135790 ClassCastException in RowData.
ClassCastException is thrown in RowData line 81(IBaseExpression expr = ( IBaseExpression ) valueExpressions.get( index - 1 );).
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/script/instance/ICellInstance.java
package org.eclipse.birt.report.engine.api.script.instance;
import org.eclipse.birt.report.engine.api.script.ScriptException;
public interface ICellInstance extends IReportElementInstance
{
	/**
	 * Get the column span
	 * 
	 * @return the column span
	 */
	int getColSpan( );
	/**