C/C++ :: Multiline Textbox And Appending A New Line

I'm having a little problem with System::String and terminating the text to end the line in the textbox, I tried adding
to the string in multiple ways (Insert, or just + " ")) but the text is still appended in one single line.

However converting a properly terminated char array to a string and appending it to the textbox works. So, let me explain my code a little more: I have a function which appends text to the textbox (I use it from a different thread thus I needed to use Invoke):

void mainTextboxAppendText(String^ text) {
if (this->mainTextbox->InvokeRequired) {
dMainTextboxAppendText^ d = gcnew dMainTextboxAppendText(this, &mainForm::mainTextboxAppendText);
this->Invoke(d, gcnew array < Object^ > {text});
} else {
this->mainTextbox->AppendText(txt + "
");
}
}

But when I try to call it multiple times with different strings then they do not appear in new lines but they're all in one single line, I've tried doing it like:

txt->Insert(txt->Length, "
");
this->mainTextbox->AppendText(tx);

I've also tried using Environment::NewLine, but it still didn't work, so what I finally came up with was converting the system string to an char array using Marshal and inserting an " " there and then converting it back to an system string, then it was ok .