Load balancing only to one node

Hello, On the below screenshot, we have 4 app servers are online for the F5, but aways, all the connections go to one of the nodes, thi isn't wanted because 4 servers should be balanced somehow and that's the meaning of F5 load balancer. Can you please suggest any setting necessary? Our main connections (80%) are from the clients with stateless webservices requests and some stateful connections (20%) via the Internet Explore.

Thanks & regards, Leon