Serial Communication command with carriage return and newline

How to write the below statement that send command to serial port in visualbasic to MatLab?

Visual Basic: MSComm1.output = "POWER, OFF" & vbCrLf

below ways are tried but it seems not working (serial port had set up bfr this statement)

1) fwrite(ComHandle, 'POWER, ON')

2) fwrite(ComHandle, 'POWER, ON \r\n')

3) sc = strcat('POWER, ON' , char(13), char(10))

fwrite(ComHandle, sc)

none of them is working

what's going wrong on the above statement