Extension folder is not refer in MainActivity, SerialConsole and The type or namespace name 'UsbSerialPort' could not be found (are you missing a using directive or an assembly reference?)

[bhuvi3613]

step1: I create new project in Xamarin android My project name is USBComm. step2: I added the UsbSerialForAndroid lib folder in my project folder, references also added. step3: then I add devicefilter file in resources folder. step4: After I follow MainActivity.cs and SerialConsoleActivity.cs file which is was refered by UsbSerialExampleApp.

Error:

1. UsbSerialPort' could not be found (are you missing a using directive or an assembly reference?
2. The type or namespace name 'Extensions' does not exist in the namespace 'Hoho.Android.UsbSerial' (are you missing an assembly reference?)
3. The type or namespace name 'Ch34xSerialDriver' could not be found (are you missing a using directive or an assembly reference?)
4. Argument 1: cannot convert from 'Hoho.Android.UsbSerial.Driver.IUsbSerialPort' to 'UsbSerialPort'

I tried to solve many times but I couldn't find any solutions so please kindly help me to solve this problem.i checked my namespace also it was correct only but eventhough this error created.