That SmartObject you are using... is it linked to the SmartBox or is it saving this data elsewhere? I think the problem is that after you submit your form, you need to load the data into the SmartObject on the workflow context. The way it looks right now is that you are using an empty SmartObject, so the error message is appropriately saying that you can't assign this task to an empty string.

We are using a smartbox. All other data is saving correctly, just not the email addresses in my populated list box. 

In the form I ask for draft of final copy, date, and client name (client contacts list box then populates based off of what client name is selected.) In the task email, I reference the date and document type, and it populates that information. It is saving in the database, it just can't distinguish the email addresses in the listbox as the recipient it needs to send the task to. 

My apologies for misunderstanding... so are the e-mail addresses that you enter in just not saving at all? I mean, that field in the SmartBox table is null no matter what you enter on the form?

I would double check that you're resolving the returned email addresses to a user as shown in the picture below. 

One note though; I have not tried recently to use a list method to return multiple users. 

If the previous method does not work a way to get around this though might be to use the Loop event and loop through your list of users, creating a task for each of them.

Hope this helps!

yes they were saving as null. We finally got it going we had to make some adustments to the smartobject settings in the control list box itself.