enums are not acceptable in signals connected using Connections

If I have a signal with some enums as a parameter, it works fine if I directly connect it in QML. But the enum can't be recognized if the signal is connected using Connections element, and complaining e.g.: QMetaProperty::read: Unable to handle unregistered datatype 'ChargingState' for property 'QDeclarativeBoundSignalParameters::state'