How to clear the trouble with the ampscript lookup function?

 %%[ VAR @EventType, @DateTime, @Address
SET @EventType = Lookup("CampaignMember_Contact_Builder", "Event_Type__c", "ContactId", _subscriberkey)
SET @DateTime = Lookup("CampaignMember_Contact_Builder", "Event_Date__c", "ContactId", _subscriberkey)
SET @Address = Lookup("CampaignMember_Contact_Builder", "Address__c", "ContactId", _subscriberkey)]%%
Having trouble with my lookup function. When called, these vars are not returning anything in preview. All data comes from Salesforce using the connector.

eg

%%[ VAR @EventType, @DateTime, @Address , @SubscriberKey

SET @SubscriberKey = AttributeValue("_subscriberkey")

SET @EventType = Lookup("CampaignMember_Contact_Builder", "Event_Type__c", "ContactId", @SubscriberKey)

SET @DateTime = Lookup("CampaignMember_Contact_Builder", "Event_Date__c", "ContactId", @SubscriberKey)

SET @Address = Lookup("CampaignMember_Contact_Builder", "Address__c", "ContactId", @SubscriberKey)]%%