diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index ab4cf06..b85d196 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -674,13 +674,24 @@ Ticket Calculator::private_GetDurationFromCost(Configuration *cfg,
 
                 // Check prepaid
                 if (!prepaid) {
-                    if ((current.time() < worktime_from) || (current.time() > worktime_to)) {
-                        qDebug() << "[STOP] * Ticket is not valid * ";
+                    if (current.time() < worktime_from) {
+                        qDebug() << "[STOP] TICKET IS NOT VALID: "
+                                 << QString("%1 (current) < %2 (start)")
+                                        .arg(current.toString(Qt::ISODate)
+                                        .arg(worktime_from.toString(Qt::ISODate)));
+                        return Ticket();
+                    } else
+                    if (current.time() > worktime_to) {
+                        qDebug() << "[STOP] TICKET IS NOT VALID: "
+                                 << QString("%1 (current) > %2 (end)")
+                                        .arg(current.toString(Qt::ISODate)
+                                        .arg(worktime_to.toString(Qt::ISODate)));
                         return Ticket();
                     }
                 } else {
-                    qDebug() << "* PREPAID MODE ACTIVE *";
                     if (current.time() < worktime_from) {
+                        qDebug() << "*** PREPAID *** Current time is before time range start, fast-forward to start"
+                                 << worktime_from.toString(Qt::ISODate);
                         current.setTime(worktime_from);
                         end = current;
                     } else if(current.time() > lastWorktimeTo) {