Create a custom marketing element

Hi all,

I follow the document in academy to create a custom marketing element https://academy.bpmonline.com/documents/technic-sdk/7-13/adding-custom-transition-flow-new-campaign-element

• In the section 6 (CREATING THE CAMPAIGNCONNECTORMANAGER REPLACING MODULE FOR ADDING THE FLOW OPERATION LOGIC), it said “create a new module schema replacing the CampaignConnectorManager”
• I can’t create a “replacing client module“ with another name “TestSmsCampaignConnectorManager”
• And I can’t inherit that module when I create a module, system said “Substitution of modules is not allowed”. After saved, the parent object “CampaignConnectorManager” will remove when refresh page.

So, what can I do?