How to Filter data from one table which does not exist in another table ?

Hi 

I was trying to filter data from table "RequestWB" which is a child table of "Requests".Now I want to exclude data that is already exists in another table "Recieved Requests". In "Recieved Requests" table I have one lookup column from Request. 

Is there any way to do this?

Filter(RequestICC,Not(ICC_Request_Org_ID in 'Received Requests'.Req_ID))

I have used this code and failed!!