Paginated report - Cascading list - coming blank

Hi,

I have a question on Cascading list in Paginated report. When I select 1 Program Group, in this case "172 East" or "172 Blann" , I get correct list of Growers associated with that Program group.

But when I select more than 1 Program Grower group, I get blank values for growers. 

How do I make it understand that give me list of 5 growers now?

Here is my parameter and it's Default value:

Here is my grower dataset which is referencing "Program Group" to get "Grower Legal Names"

I am not sure what am I doing wrong?

I applied same kind of logic to get values for "Program Group" where I am getting multiple values. So I am not sure what am I missing in case of growers.

Thanks in advance,

-rk