MS CRM CHART Axis Labels sorting

In the above chart my horizontal axis labels are text field in which am storing the label formats  as 01jan_Act, 01Jan_Obj  ..and so on . i had to go for prefixing with 01 ,02 so on .i have also added the below line chart xml.

 <order alias="_CRMAutoGen_groupby_column_Num_0" descending="false"/>. 

then i could achieve the month labels in order .

is it possible with out prefixing 01 ,02 so on.

Thanks ,

Mohammed Waseem