No one is probably trying to even do this anymore due to the new Dell switching lines, but thought I would see if I could help. I had this issue the other day, and it took a good bit of googlefu before I could find my answer .
The problem I had was getting SSH enabled on a Dell PowerConnect 7048P. I created my user/passwords , and then generated my certificate, and then enabled the SSH server.. I got this error
PC-7048(config)#crypto key generate rsa
RSA key generation started, this may take a few minutes……..
RSA key generation complete.
PC-7048(config)#ip ssh server
SSH could not be enabled.
Hmmm… Why is that, all of my needed components are there, so why is it not working. The reason is there is no Cert to be used by SSH. These models use the Digital signature Algorithm (DSA) Certificate instead of the RSA cert. SO we need to create the DSA Cert.
PC-7048(config)#crypto key generate dsa
DSA key generation started, this may take a few minutes………………….
DSA key generation complete.
PC-7048(config)#ip ssh ser
No error!! and it works just fine.
Good reading for the comparison of RSA vs DSA: http://security.stackexchange.com/questions/5096/rsa-vs-dsa-for-ssh-authentication-keys