What am doing wrong? Creating a relationship between two tables.

The situation,

I have four different bank account numbers. I created a table with the field names "ID" (assigned by Access), "BankName", and "AccountNumber".

I'm trying to create a relationship between my imported bank transactions table, that has an equivalent account number field, to the "AccountNumber" field in my bank account table. In my mind this should be a one to many relationship and I should be able to create a subdatasheet, but Access isn't having it. It's creating a one to one relationship and the subdatasheet records do not match their parent record. Any suggestions?

Thanks ranman256,

I found the solution minutes after I posted this. I was attempting the incorrect "Join" between the tables.