DAX why the error when the focus has changed

[garythomannCoGC]

sql programmer having 'fun' with dax :}    Current post while trying to get a query to work, dax syntax

Now different question, why the exact same query works for one return and not the other?

pml var return focus

pml_id return focus

Hilarious, now expand the query and new focus works!?   

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Why no data returned when  'Measure Benefit Master'[PM IDId] = 3921  in the dataset shows 4 rows?

Try with direct literal.

dataset table mbm.PM IDId  filtered for 3921

>>  answer is lack of data integrity in the data,   'Measure Benefit Master'[DIR] = "CO"   has different values, remove and working :}

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[OwenAuger · Accepted solution]

Just catching up with your question here 🙂

One key point: DAX queries can only return tables, not scalar values.

So RETURN pml will result in an error in the above queries.

Contrast with measures that must return scalar values.