You have no personal gateways installed

HI ,

Below are important points you need to ensure for configuring the Gateway or Troubleshooting : 
1) Gateway has the datasource configured on the machine ( Clients and others) like in your case oracle also and it should have connectivity. 

2) Hope you have Enterprise Gateway instead of Personal because you wont be able to see Personal Gateway of other . 

3) If its Enterprise Gateway ( Until and unless you are not using Personal) make sure you have added user to use it i.e. permission for the user ( Manage Gateway > Choose Gateway > 3dots > Add users ) 

4) If you are using personal gateway the service and other stuff is running correctly .

Hope this helps. 

Regards

Mahak