Unable to send v3 trap using snmptrap

Question

I am trying to send snmp v3 trap using snmptrap command on ubuntu 12. I tried:

sudo snmptrap -v 3 -c 1 localhost -a MD5 -A abcdefgh -l noAuthNoPriv -u myuser

sudo snmptrap -v 3 -c 1 localhost -a MD5 -A 1.2.3 -l noAuthNoPriv -u myuser

sudo snmptrap -v 3 localhost -a MD5 -A 1.2.3 -l noAuthNoPriv -u myuser

but keep getting:

-A: Unknown Object Identifier (Sub-id not found: (top) -> -A)

I also tried:

sudo snmptrap -v 3  -a MD5 -A abcdefgh -l noAuthNoPriv -u myuser localhost:162

and got:

Missing up-time parameter

Can anyone see what I am doing wrong.