/assist jhazz
/cast [target=focus, nodead, harm] Smite

means you are trying to cast Smite on your focus (target=focus). You have set the target using assist jhazz so remove target:

/assist jhazz
/cast [nodead, harm] Smite

If you are using focus to set your main with /focus jhazz you can use the following for any damage spells with your slave:

#showtooltip
/cast [exists,harm,nodead] Smite
/stopmacro [exists,harm,nodead]
/a Focus
/cast Smite