How to apply dillthru based on quarter

[midhl]

I have a report where in we are using a period column in a crosstab.There is a prompt for this period which includes monthly,quarterly and annual.Based on the prompt selected data in the period changes where in if monthly is selected period in crosstab displays monthly,if quarterly then quarterly is displayed and the data  in the report is filtered accordingly.The issue is when the drill thru is applied on the cross tab we are able to create a filter for monthly period and yearly period in the child report.However when we come to quarterly since if a quarter is chosen data needs to be filterd for 3 months of that particular quarter,am unable to achieve it using expression data between month1 and month3.There is an erro message displayed that the syntax error near  = .One more things is month,year and quarter columns are not there in the model and are derived from period column which contains year and month.COuld somone help with this

Thanks