GTK Widget assertion problem

[Michael T. <myso77 seznam cz>]

Hi,
 I have a problem, when I try to access the GTK progress bar out of the function it was created in.
I have a global variable 
GtkWidget *progressBar;
so that I can access the progress bar from all the functions and different files in the project.
When I initilize the bar and call functions to change it's values in the same function, everything works 
fine. I used the following code:
progressBar = gtk_progress_bar_new();  
gtk_box_pack_start (GTK_BOX (vboxGr), progressBar, FALSE, FALSE, 0);
gtk_widget_show (progressBar); 
gtk_progress_bar_set_text (GTK_PROGRESS_BAR(progressBar), "hello");

However, when I call the functions outside of the function where the progress bar was created I get an 
assertion error. The following funcion is defined in the same file and I've used similar concepts for various 
other widgets, it doesn't work just for progress bar.
The code is as follows>
void progress()
{
  int i;
  for(i=0;i<1000;i++)
  {
    gtk_progress_bar_pulse (GTK_PROGRESS_BAR (progressBar));
    while (gtk_events_pending ())
    gtk_main_iteration();
  }
}

The error I get is:
Gtk-CRITICAL **: gtk_progress_bar_pulse: assertion `GTK_IS_PROGRESS_BAR (pbar)' failed

 I've tried to use the extern declaration, I've tried to combine the code and modify various files in various 
ways just to make the program really convinced it's working with a progress bar, I still get the same error. 
It works only when I use it inside the function that it was created in, which is of course unimportant, 
because I need to access it from various callbacks, etc.

This approach works with different widgets perfectly. For instance this function works great:

void textField_push(char message[100]){
        extern GtkWidget* textField;
         GtkTextBuffer *buffer; 
        
        buffer = gtk_text_view_get_buffer(textField);
        gtk_text_buffer_set_text(buffer, message, -1);

}

Please help.

thanks,

Michael