Try this (tested only for syntax errors):

DEFPARAM CumulateOrders = FALSE
ONCE BuyCond  = 0
ONCE SellCond = 0
IF OnMarket THEN
   BuyCond  = 0
ENDIF
IF Not OnMarket THEN
   SellCond = 0
ENDIF
Ema144 = exponentialaverage[144](close)
Ema89  = exponentialaverage[89](close)
Ema34  = exponentialaverage[34](close)
MyMacd = Macd[12,26,9](close)
StocK  = Stochastic[8,4](close)
c1     = Ema34 CROSSES OVER Ema89
c2     = MyMacd > 0
c3     = StocK > 30
IF BuyCond = 0 THEN
   BuyCond = c1 AND c2 AND c3
   MyPrice= Ema34                         //buy at Ema34  or
   //MyPrice = low[1] + (range[1] / 2)    //buy at half of previous candle
ENDIF
// Keep entering a pending orders bar after bar till Onmarket
IF BuyCond THEN
   IF close > MyPrice THEN
      BUY 1 CONTRACT AT MyPrice LIMIT     //buy at a better price
   ELSE
      BUY 1 CONTRACT AT MyPrice STOP      //buy at a worse price
   ENDIF
ENDIF
IF SellCond = 0 THEN
   SellCond  = Ema34 CROSSES UNDER Ema144
   SellPrice = Ema34
ENDIF
// Keep entering a pending orders bar after bar till Exit
IF SellCond THEN
   IF close > SellPrice THEN
      SELL 1 CONTRACT AT SellPrice STOP   //exit at a worse price
   ELSE
      SELL 1 CONTRACT AT SellPrice LIMIT  //exit at a better price
   ENDIF
ENDIF