matlab test and measurement tool

Hi everone

I conncted my ALTERA DE2 FPGA board using the UART (serial protocol ) to the computer . the thing is that when i send data and using external program such as Realterm I can see the data that I send using the RS 232 . but when I open matlab and press the matlab test and measurement tool for some reason it cannot identify my RS232 cable and as you can see in the pic it is written :

No instrument was identified .

any ideas how to fix it ?

of course when I use matlab I close the Realterm program