OQL where clause for boolean attribute

Hi  I try to retrive dataset by OQL but the result doesn’t come as expect. by reducing the clause, I found the problem is the boolean attribute in where clause.  In my “Poline” model, “IsClosed” is a boolean type.  I tried to use below OQL to fetch all opened order, but it seems always return the closed order, which means it filter out “IsClosed” true, ignoring the Not in front of it. Did I do anything wrong? Below is my OQL, thank you in advance for any suggestion. select  PoLine/PoID as POID, PoLine/RequestQTY as requestQTY,backorderQTY as BackorderQTY   from MyFirstModule.POLine as PoLine where not PoLine/IsClosed  
1 answers

See the 3rd and 4th buttons on https://mydemoversion8-sandbox.mxapps.io/p/OQL for examples on the boolean.

This works for your situation:

where PoLine/IsClosed = false