Create a formula (BB38893) with the following text:

if {CnGf_1Ins_1.CnGf_1Ins_1_Date} in Date (2001, 01, 01) to Date (2001, 03, 31)

then {CnGf_1Ins_1.CnGf_1Ins_1_Amount}



Note: Substitute Date(2011, 01, 01) and Date(2001, 03, 31) with your desired date range