@Poon Cheuk Hin Christophe Thanks for the details. As you said The second "Join Data" is unable to combine the first "Join Data" dataset with another dataset named "Aruoba-Diebold-Scotti Business Conditions Index". Are you seeing any error details?. If yes please share the same.
Here is the document to Join Data in the Designer.
https://learn.microsoft.com/en-us/azure/machine-learning/component-reference/join-data
To check further on this issue, Please share details of your experiment and issue from the ml.azure.com portal for a service engineer to lookup the issue from the back-end? This option is available from the top right hand corner of the portal by clicking the smiley face, Please select the option Microsoft can email you about the feedback along with a screen shot so our service team can lookup and advise through email.