When selecting many users (after applying a filter on a view) I have a custom action that has the following code.

1. void SMS.sendsms(Setup_Customer_Contacts VCustomer)
2. {
3.     querystring = "";
4.     for each cust in VCustomer
5.     {
6.         querystring = querystring + "custID=" + cust.ID + "&";
7.     }
8.     openUrl("#Form:SMS_Content?" + querystring, "popup window", "height=200,width=400");
9. }

For the popup window, on "submit" I have the following code:

1. l = input.custID;
2. for each cust in l
3. {
4.     VCust  =  Setup_Customer_Contacts  [ID == cust];
5.     if ((VCust.Active  =  "Yes")  &&  VCust.Method.contains("Text"))
6.     {
7.         //SEND MESSAGE
8.     }
9.     openUrl("#Script:dialog.close", "same window");
10. }

Here is my problem:

My lookup field custID is only accepting one ID at a time. When I try to pass multiple ID's I get an error saying. "The parameter custID should appear at most 1 time(s)."

Do you have any idea on how I fix this? Any help would be GREAT! Thanks!