SerialMessagePort contructor arguments

I am having an issue with SerialMessagePort. The constructor does not accept either 8 or 9 arguments?

The class contains the following:
protected SerialMessagePort(SerialPortName portName, byte[] suffixDelimiter, bool preserveDelimiter, int baudRate = 9600, int dataBits = 8, Parity parity = Parity.None, StopBits stopBits = StopBits.One, int readBufferSize = 512);

protected SerialMessagePort(SerialPortName portName, byte[] prefixDelimiter, bool preserveDelimiter, int messageLength, int baudRate = 9600, int dataBits = 8, Parity parity = Parity.None, StopBits stopBits = StopBits.One, int readBufferSize = 512);

I have tried both and each time VS indicates CS1729: ‘SerialMessagePort’ does not contain a contructor that takes 8/9 arguments.