gtk textview问题……

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int print_to_text_view(char *msg,int type)
{
while (gtk_events_pending())gtk_main_iteration();
buffer=gtk_text_view_get_buffer(GTK_TEXT_VIEW(tcptext));
gtk_text_buffer_get_end_iter(buffer,&end);
gtk_text_buffer_insert(buffer,&end,g_locale_to_utf8(msg,-1,NULL,NULL,NULL), -1);
gtk_text_view_set_buffer(GTK_TEXT_VIEW(tcptext),buffer);

return 1;
}
上面这个往textview中插入数据的函数在运行时会出现
(raw:2871): Gtk-CRITICAL **: gtk_text_buffer_insert: assertion `text != NULL' failed
这是为什么阿？