doubt in cognos report studio

[sowjanya batchu]

hi

i have a doubt i have to display month name beside the report name.  In query section i hv created a data item named computed and i have written a case condition in it as

case extract(month,[effdate] when 1 then 'january' etc

and in report page i'm calling the query calculation beside report name and i'm displaying the computed value in it
but if i'm selecting multi-value in month prompt page it is displaying only first month name as january not as april,january,march etc