Lookupvalue error: A table of multiple values was supplied where a single value was expected.

Hi guys,

I'm trying to retrieve a value from another column using the DAX function LOOKUPVALUE(), but I'm getting a very annoying error: A table of multiple values was supplied where a single value was expected.

I'm trying to execute the following DAX formula:

next trans name = VAR visord = [order_within_visitor] VAR visid = [visitor_id] RETURN 
if(visord = MAXX(FILTER('public pageview', [visitor_id] = visid), 'public pageview'[order_within_visitor]), 
"Exit", 
LOOKUPVALUE([page_transname], 'public pageview'[order_within_visitor], (visord+1), 'public pageview'[visitor_id], visid  ))

I want to retrieve the next value of a series and put it in the "next trans name" field. I need to check if it is the last value of the series, because it should have a different behaviour when it is. If it's not the last number in the series, it should lookup the page_transname for that record and put it in the "next trans name" field.

I have something like the following datastructure (very much simplified):

Does someone know what the problem might be?

Thanks!