Unable to resolve #Multivalue problem

I have thousands of records. A sample table is as below

Job ID     Task ID      Task Name     Task Start Date     Task End Date

A               A1              One               28-Apr-2008          28-May-2009

B               A2              Two               #MULTIVALUE     #MULTIVALUE

C               A10            Ten               30-Jan-2013          30 Dec-2014

I have created a measure using Max for both Task Start Date and Task End Date. Encountered #MULTIVALUE error for some records. I have tried playing around with the table properties and it doesn't work.

Should a If Else statement be used?  How do I go about it?

It seems like WEBI could not differentiate that there could be other Task ID and/or Task Name with the same Task Start/End Date, though each Job ID will not have two exact Task ID and Task Name.

Thank you.