Sorry to confuse you! The problem is I cant upload screenshots of my chart here.
The above is the data in my excel document and as you can see there are three rows (Jan-2011, Jul-2011 and Oct-2011) with the same date (0) for both "Downtime" and "Occurence"
When I try to show these data on the chart in my X axis I will have (from left to right):
2009 Average, 2010 Average, Oct-2010, Nove-2010, Dec-2010, Jan-2011, Feb-2011, Mar-2011, Apr-2011, May-2011, Jun-2011, Jan-2011 (instead of Jul-2011), Aug-2011, Sep-2011, Jan-2011 (instead of Oct-2011).
Also if I change months name on my chart manually it will change all the values to the value I changed. For example if I change Jan-2011 for my last month to Oct-2011, other my simillar vlues will change to Oct-2011.
I want to prevent that and have months in order on the X Axis of the chart.
Hope I explain it clear enough!