Bug 156166 Error occour when previewing attached report in web viewer.
Decription:Error occour when previewing attached report in web viewer. Steps to reproduce: 1.run attached reports in web viewer. Expeceted results: preview properly Actual results: Error occour when previewing the reports in web viewer while it works properly in html and PDF
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/BindingColumnsEvalUtil.java
if ( evalHelper.contains( columnName ) )
				{
					getValue = true;
					exprValue = evalHelper.getValue( columnName );
				}
			}
			
			if ( getValue == false )
			{
				if ( exprType == MANUAL_BINDING )
					exprValue = ExprEvaluateUtil.evaluateExpression( bindingColumn.baseExpr,
							odiResult,
							scope );
				else
					exprValue = ExprEvaluateUtil.evaluateRawExpression( bindingColumn.baseExpr,
							scope );
			}
		}
		catch ( BirtException e )
		{
			exprValue = e;
		}
		
		return exprValue;
	}
	
	/**
	 * A simple wrapper for binding column
	 */
	private class BindingColumn