HOW to upload a sketch to MKR1400 GSM

As you can see, I do have no idea that´s why I ask the question above.
I´m using this easy blink code but there is something wrong with me.

The combination between the MKR 1400 GSM and the CP 2102 does not work.
It finds the device but for upload, it's writing "No device found on COM12"

or this: java.io.IOException: jssc.SerialPortException: Port name - COM12; Method name - setEventsMask(); Exception type - Can't set mask.
at processing.app.Serial.dispose(Serial.java:166)
at processing.app.SerialMonitor.close(SerialMonitor.java:116)
at processing.app.AbstractMonitor.suspend(AbstractMonitor.java:90)
at processing.app.Editor$DefaultExportHandler.run(Editor.java:2160)
at java.lang.Thread.run(Thread.java:748)
Caused by: jssc.SerialPortException: Port name - COM12; Method name - setEventsMask(); Exception type - Can't set mask.
at jssc.SerialPort.setEventsMask(SerialPort.java:279)
at jssc.SerialPort.removeEventListener(SerialPort.java:1064)
at jssc.SerialPort.closePort(SerialPort.java:1090)
at processing.app.Serial.dispose(Serial.java:163)
... 4 more

Can somebody tell me what´s wrong with me???

THX from Berlin

How do you know that the MKR1400 is on COM12 ?