1- Use numbers in "gk prefix" field in SMC2.0 web page not a characters . For Example "010"、“0086”and so on. Check the attached image.
2-Let the prefix is same at the MCU and the GK.[check the attached image]
3-check the “Access password” . [The default access password is “123456” ].
4-Check if the MCU is registered on GK or not .
5-You can delete the “GK Authentication Password” if you are not using an authentication .[Keep the field empty ]