LEFT JOIN Syntax - it doesn't seem to work.

LEFT JOIN Syntax - it doesn't seem to work.

I have some test data in ZohoCRM with 10 contacts, and a few 'calls' logged against those contacts.

I want to produce a report that shows the last time each contact was called.

This SQL syntax doesn't work:

SELECT "Contacts"."CONTACTID", "Contacts"."Last Name", MAX("Calls"."Call Start Time")
FROM "Contacts"
LEFT JOIN "Calls" On "Contacts"."CONTACTID" = "Calls"."CONTACTID"

The output only shows the 1 contact that has a call logged, but I need the report to show every contact in the contacts table (and a null value for the 'Call Start Time' when no calls have been logged).

How do I fix this?

Thanks in advance.