Routine in sap bi

HI Experts,

Good day!

I have requirement like source data is coming as calday which need to convert to quarter and i tried the routine but it throwing the error so any one please check the below code.

calyear = calday+0(4).

calmonth = calday+4(2).

case calmonth.

When '01' or '02' or '03'.

calquarter = '01'.

When '04' or '05' or '06'.

calquarter = '02'.

When '07' or '08' or '09'.

calquarter = '03'.

When '10' or '11' or '12'.

calquarter = '04'.

endcase.

Regards

RK