gtk_text_insert - beginner

[hracekp volny cz]

Hello all

Firstly I am begineer with developing GTK+ and I using Glade and
Anjuta. I have got simple problem.
If I develop new application, I create GUI with Glade and all is OK.
I have got button1 widget there and text1 widget there.
If I insert signal on_button1_clicked I want after this click insert
to the text box some text, but compiler says me that text1 widget is
undeclared symbol.

void on_button1_clicked ...
{
        gtk_text_insert(GTK_TEXT(text1),NULL,NULL,NULL,"some text",-1);
}

Can you help me with problems, where I wrote code.
Can you send me emails to my address and to the conference.

Thank you very much
Petr