Option to select CRM Campaign unavailable in Account Engagement

Is the box for 'Use Salesforce to manage all campaigns' checked? 

Do not select ‘Use Salesforce to manage campaigns’ option until you have connected all of your existing Account Engagement campaigns. For more info, check this: Connected Campaigns FAQ. 

1. In pi.pardot.com, open Settings and click Edit. Scroll to Connected Campaigns.
   or, in the Lightning app, click the Account Engagement Settings tab and then select Connectors. Click the gear icon to edit the Salesforce connector, and select the Campaigns tab.

2. Uncheck the box for Use Salesforce to manage all campaigns. 
3. Save Account and then try connecting your campaigns.