# Troubleshooting

Please refer to our [Knowledge Base](https://support.crosscontrol.com/knowledge-base) for further information and
troubleshooting guides.

## Plug-in not available after installation

Verify that the plugin is activated in Qt Creator:

1. Open `Help` and select `About Plugins`.
2. Locate section `Utilities` in the list of plugins.
3. Verify that `LinXManager_DataEngine` is available and loaded.

## Application does not connect with Data Engine

Verify that Data Engine is running on `localhost` if the application outputs any of the following messages:

* `connect: Connection refused written`
* `connect: Connection refused`
* `virtual void QtObserver::HandleMissedHeartBeat() Heartbeat is late!`

## Signal value is not updated in GUI

### "Cannot read property 'value' of undefined"

Verify that the referenced name matches the configured name.

``` qml
Text {
    text: dataEngine.engineRPM.value    // OK
}

Text {
    text: dataEngine.enginRPM.value     // Not OK, misspelled signal name
}
```

## Signal value is not possible to set

### "Cannot assign to read-only property "value""

Verify that the signals `Signal Type` is configured as `PRODUCER`.

``` qml
Button {
    text: "Request stop"
    onPressed: dataEngine.producerSignal.value = true   // OK
    onReleased: dataEngine.consumerSignal.value = false // Not OK 
}
```

### "Unknown signal id (provided id: 0)"

Signal is written before the subscription phase with Data Engine is completed. Verify that Data Engine is running on
`localhost`. If Data Engine is running, verify how the signal is set from QML. Assign a value to the signal rather than
using of using `setValue()` is recommended.

``` qml
Button {
    text: "Request stop"
    onPressed: dataEngine.requestStop.value = true      // Recommended
    onReleased: dataEngine.requestStop.setValue(false)  // Not recommended 
}
```