"Expression could not be evaluated" on debugging

 

In the watch panel, testFunction() could not be evaluated.

While testVariable returns properly the value from testFunction() (1234)


//+------------------------------------------------------------------+
//|                                test_expression_not_evaluated.mq5 |
//|                                  Copyright 2021, MetaQuotes Ltd. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2021, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"

//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int testFunction(){ return 1234; }
int OnInit()
  {
//---
   int testVariable = testFunction();
   DebugBreak();
//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Expert deinitialization function                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
//---
   
  }
//+------------------------------------------------------------------+
//| Expert tick function                                             |
//+------------------------------------------------------------------+
void OnTick()
  {
//---
   
  }
//+------------------------------------------------------------------+
 
The watch panel displays variables. You can't call functions.
Reason: