Hi all, I have a question why such a query works

SELECT COUNT() FROM OpportunityHistory WHERE  OpportunityId IN (SELECT Id FROM Opportunity WHERE CreatedDate = THIS_WEEK)

 and such an error

SELECT COUNT_DISTINCT(OpportunityId) FROM OpportunityHistory WHERE  OpportunityId IN (SELECT Id FROM Opportunity WHERE CreatedDate = THIS_WEEK)

ERROR:

 Invalid argument supplied for foreach() in /var/www/dev.local/system/libraries/salesforce/SforcePartnerClient.php on line 344

Hi all, I have a question why such a query works

SELECT COUNT() FROM OpportunityHistory WHERE  OpportunityId IN (SELECT Id FROM Opportunity WHERE CreatedDate = THIS_WEEK)

 and such an error

SELECT COUNT_DISTINCT(OpportunityId) FROM OpportunityHistory WHERE  OpportunityId IN (SELECT Id FROM Opportunity WHERE CreatedDate = THIS_WEEK)

ERROR:

 Invalid argument supplied for foreach() in /var/www/dev.local/system/libraries/salesforce/SforcePartnerClient.php on line 344