Combat Medic Archive

what am i doing wrong, i have one macro to i can target myself - /tar iasha - then the next button i press (manually) is where ive already loadaed a bacta toss enhancer into my F4 button. then occasionally i hit for bacta toss enhancer and it says "That is not a valid pvp target" constantly, then in my next fight - no problem? any ideas?

Lag.