Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.
Alternatively, you may set the environment variables GTK_CFLAGS
and GTK_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
Installing "gnome-core-devel" was the solution for my problem:
sudo apt-get install gnome-core-devel