My employer purchased 3 new switches (1-s3048/2-s4048) that are Dell to go along with the new server's we purchased from Dell. I am able to gain connectivity to the network, ping back and forth, and I've even accessed a port (on the Dell) via my laptop and am able to connect to other switches (Cisco) remotely via ssh. However, when I attempt to connect the Dell switches via ssh/putty nothing happens. I get the following log message below on the Dell switch:

*Login Failure for user admin on line vty 0. *

Has anyone experienced this?  I can't post my configs because I work in a secure closed network. I think I tried everything I can think of the last three days. Also, I am authenticating through a Radius server.