I need some help in creating an effective formula to help me return a result into a field if the effective date is within the results column. Also want the formula to be calculated if the discontinue date has not expired.

Here is a snapshot of what I am looking to do. Project

Where as "T" will only return if effective date is 04/01/2015-04/30/2015 and still within the discontinue date. (T calculates by looking up a part number volume for that given month) I hope this is clear.

Thank you.