serial port Invoke call

hi -
I'm using VS2010 and .net4.0 with a windows form applications.  
I have successfully used the following code to handle the return data from a serial device to pass the received data to the original thread:

void port_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
int numBytesRead = port.Read(receiveBuffer, 0, 200);
                    UpdateDisplay ud = new UpdateDisplay(UpdateDisplayMethod);

                    if (numBytesRead != 0)
                    {
                        Invoke(ud, new object[] { receiveBuffer, numBytesRead });

                    }
}

I have a slightly different flavor of an application where I create a class which the above code is embedded in. when I try to paste in the invoke code, VS2010 flags it with this error:
Error      29 Cannot access a non-static member of outer type 'System.Windows.Forms.Control' via nested type 'Control_Editor.CT_UI_Control.MatrixDisplay'

 the windows form code creates the class with this code:
MatrixModule = new MatrixDisplay(portNameitem);
I don't understand why i'm getting the error, and more importantly, I don't know what to do about it.
thanks,