Dates by Month on X-Axis in Horizontal Stacked Bar Chart

Hi all. Sorry for a reply to an old thread. I have a stacked Bar chart in Excel 2010. I've added a secondary horizontal date range but when I right click and format axis I have no date options like the excellent example I downloaded from this thread. I have my chart in the same excel workbook that the example is opened in on another tab. I can see the date options on the example but not on mine. The charts appear to be the same type.. Any ideas?