Present versions of OOo/SRB uses Charts in reports.
When chart module was integrated into SRB used simple method to select data for
chart, the field order. The fields added not with field name, only a number
starting from 0.
If I have table with field names: ID, StartDate, Age, Height, Weight. 
Then in SRB Data range it will 0,1,2,3,4.
When you want to select one concrete field, you must remember to the place in
the field list.

I suggest to use Field name instead of numbers, in form [Fieldname].