Hi @jpacheco 

You should specify the value for "Unique Approval?" in the lookup

Is the column "Unique Approval? of Boolean type? You could try - Yes/No or or true/false.
Boolean: A true/false value. Does not need to be surrounded with quotes.
 

lookup("_SetOfBooks","Unique Approval?", true, "Approver Email")

Pls note that may return more than one (multiple) results or return just the first result that matches the condition.

Refer to the Help for more details

https://help.nintex.com/en-US/office365/Forms/ResponsiveClassicForms/ReferenceOther/LookupRuntimeFn-ref.htm 

@Garrett ,

Thanks for your reply and I see that it worked! But I guess I failed to mention also that, IF a certain selection is made that sits under “Title” (ex. AED Books) and the “Unique Approval?” is checked, grab the email listed for that person…

Will an If statement have to be inserted before it?

ifElse("Unique Approval?",True,) lookup("_SetOfBooks","Unique Approval?", true, "Approver Email")

Thanks!!

@jpacheco 

The Lookup function is mainly performed using a unique key value eg “Id”.

It is possible to have 2 or more conditions using a workaround.
When you have multiple conditions, you need to create a new column which you combine all the values and ideally all the values should be of the same type eg String.

Combine Title + Unique Approval into Title_Unique_Approval

Title	Unique Approval	Title_Unique_Approval	Approval_Email
AED Books		AED Books - YES	garrett@example.com
AND Books
ADA Books

lookup("_SetOfBooks","Title_Unique_Approval", “AED Books - YES”, "Approver Email")

@Garrett ,

This looked like it was going to work but after I added the column, concatenated both columns to get the title+Approval, nothing displayed…

lookup("_SetOfBooks","Title_Unique Approver"," AED Books - TRUE","Approver Email")

Is it possible to use something else to identify the value that sits in “Title_Unique Approver”?

What does this returns?
lookup("_SetOfBooks","Unique Approval?", true, "Title_Unique Approver")
Use that as the value to filter (parameter 3)

The lookup function searches for exact match.

lookup("_SetOfBooks", "Title_Unique Approver", " AED Books - TRUE", "Approver Email")

This looked like it was going to work but after I added the column, concatenated both columns to get the title+Approval, nothing displayed…

What this means is that no match was found. You need to refine the Query 
 

Is it possible to use something else to identify the value that sits in “Title_Unique Approver”?

You mean like a partial match or “contains” function. Sorry NO

@Garrett ,

I figured out another route.