no communication established

i tried a few readline functions for C++/CLI on my computer and none of them are working, below is a example of my code
if(this->serialPort1->IsOpen){
this->textBox2->Text=String::Empty;
try{
this->textBox2->Text=this->serialPort1->ReadLine();

}
catch(TimeoutException^){
this->textBox2->Text="Timed out Exception";
}

}
else
this->textBox2->Text="Port isn't Opened";

}
could anyone point out to me what is wrong with my program? i can't seem to get any data back from my PLC
if possible i would like a code on how to do it
if it changes anything my PLC is a Panasonic PLC