Bug 135465 [smoke]An error occurred when new a casading Parameter
Description: An error occurred when new a casading Parameter Step to reproduce: 1.new a sample db data source and data set 2.New a cascading parameter group, named "gp1", 3.select the data set, then create two cascading parameters, one is row["customernumber"], named p1; the other is row["customername"] Actual result; error message occurred repeatly
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
{
							value = LABEL_SELECT_A_VALUE_COLUMN;
						}
						else
						{
							value = LABEL_NO_COLUMN_AVAILABLE;
						}
						break;
					}
					case 2 :
					{
						value = getColumnName( paramHandle.getLabelExpr( ) );
						if ( value == null )
						{
							if ( getDataSetColumns( ).length > 0 )
							{
								value = LABEL_SELECT_DISPLAY_COLUMN;
							}
							else
							{
								value = LABEL_NO_COLUMN_AVAILABLE;
							}
						}
						break;
					}
				}
			}
			if ( value == null )
			{
				value = "";