undefined reference to `soup_session_new'

undefined reference to `soup_session_new'

I am trying to make a get request in vala following this:
https://wiki.gnome.org/Vala/LibSoupSample. I do exactly what it says and
the compiler throws this:
Connection.vala.c:(.text+0x76): undefined reference to `soup_session_new'
collect2: ld returned 1 exit status
error: cc exited with status 256
Compilation failed: 1 error(s), 0 warning(s)
And this is the result from pkg-config --libs --cflags libsoup-2.4
-pthread -I/usr/include/libsoup-2.4 -I/usr/include/libxml2
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include
-lsoup-2.4 -lgio-2.0 -lgobject-2.0 -lglib-2.0
I have vala 0.20.1. runing on elementaryos (the newest stable version).
Any ideas?