Always add language='en_US' AND publishstatus ='online' in the Query.
Sample Query:
String strSOQL = 'SELECT Id, ArticleNumber, Title, LastModifiedDate, CreatedBy.Name FROM Knowledge__kav WHERE language=\'en_US\' AND publishstatus = \'online\'';
Check the below link for more info
https://help.salesforce.com/apex/HTViewSolution?id=000113362&language=en_US
Cheers!!!
Sample Query:
String strSOQL = 'SELECT Id, ArticleNumber, Title, LastModifiedDate, CreatedBy.Name FROM Knowledge__kav WHERE language=\'en_US\' AND publishstatus = \'online\'';
Check the below link for more info
https://help.salesforce.com/apex/HTViewSolution?id=000113362&language=en_US
Cheers!!!