QJSEngine set property before Function call

I have the following code to evaluate a code in QJSEngine:
QString jsCode = QString("(function myFunction() {return (%1);})();").arg(code); m_jsengine>globalObject().setProperty("myFunction", jsCode); QJSValue fun = m_jsengine>evaluate(jsCode); for (int i = 0; i < 500; ++i) { m_jsengine>globalObject().setProperty("_X_", QString("%1").arg(i)); if( i == 10 ) { qDebug() << "_X_ Value is : " << m_jsengine>globalObject().property("_X_").toString(); fun.call(); }
where code is the formula. (ex.A*B/2) with initial value A as 10 and B as 12. When I execute the code, the expected result is, each time the X changes and the output should change. But the result is always the same. So I knew the set property in the loop really did not change the value of X variable.
A little help is highly appreciated.