SSIS expression: Int to String datatype

Hi ,

I have column which is Int type. In the expression, i need to check whether it contains blank or null value. if yes then mark it as "Unspecified" else keep it as it is

I have written something as :

(DT_WSTR, 4) (SupplyPlanIntervalDays == "" ISNULL(SupplyPlanIntervalDays ) ? "Unspecified" : SupplyPlanIntervalDays)

please help me

Regards, Kishlay Anand