It’s due to narrow SL and TP, try changing both to, say, 40 or 50 andit’ll work.

Yes, there were a couple of additional issues:

• use STOP instead of LIMIT to exit, as you are placing a pending order to exit at WORSE price
• use a variable (I named it FLAG)  to signal that an exit at breakeven has been triggered, as it must be placed each new bar until hit (or TP is hit, of course); the exit order must be outside the conditional IF…ENDIF block.

I tested this code on Dax, 4h TF:

IF close crosses under average[100] and not onmarket THEN
   SELLSHORT 2 Perpoint AT market
   flag = 0
ENDIF
// Conditions to exit short positions
IF SHORTONMARKET AND close < tradeprice - 6 THEN // if the price moves 5pts in my favour…
   if countofshortshares = 2 then
      Exitshort 1 PERPOINT at market //close half of the trade
      //SoldHalf = 1
      breakevenlevel = tradeprice //…calculate the level for a stop 5pts below the trade open price…
   endif
   If COUNTOFSHORTSHARES=1 then
      flag = 1
   endif
Endif
IF flag = 1 then
   Exitshort 1 PERPOINT at breakevenlevel stop
endif
// Stops and targets
SET STOP ploss 500  //8
SET TARGET pPROFIT 500  //14
//
graphonprice tradeprice(1)
graphonprice breakevenlevel coloured(255,0,0,255)
graph close < (tradeprice - 6)

Keep in mind that you can now use the SET STOP BREAKEVEN instruction which is the best way to ask the broker your stoploss at breakeven