Creating a custom column with field value populate from another table using M query

Hi all,

I am trying to create a custom column in one of the table below (IE36_Append_main) and this custom column is going to populate the value based on another field in another table (i.e. License Plate Relevancy [License Plate Relevant]). Both of the two tables can be linked using Vehicle Type as the key. (see following data model).

I am coding the followng style but it doesn't work:

if License Plate Relevancy.[Vehicle Type] = [Veh. Type]

   then License Plate Relevancy.[Licence plate relevant]

else 0

Please help. Thanks. Tuff