[ApolloScripter]

This is not specifically an error, but rather a warning, in this case is because your code is disorganized, try to put it like this:

pawn Code:

if(sInfo[MedikuDarbas][playerid] != 0)
    return SendClientMessage(playerid,RAUDONA,"[SERVER]Tu jau dirbi čia!");

And check if the variable type declares is specific to the player, this warning can be caused by a statement that does not agree with the use of the variable, send-me the variable to take a look