Problem with kernel snap

I was compiling a new kernel which can support new usb device for raspberry.
But the image generated by .model can boot success at the first time.
After set the email and reboot, it will report bad linux arm image and cannot find .snap/*.img.
My *.json is :
“type”: “model”,
“authority-id”: “KNuf5O5acEuveKsJLuZAHKs6CXEoHTGx”,
“brand-id”: “KNuf5O5acEuveKsJLuZAHKs6CXEoHTGx”,
“series”: “16”,
“model”: “test”,
“architecture”: “armhf”,
“gadget”: “cm3”,
“kernel”: “pi2-kernel”,
“timestamp”: “2018-05-22T06:16:19+00:00”

I type 'ubuntu-image -c stable -o test.img test.model ’
I don’t know what wrong with my steps, can anyone help me?