[Vala] How to make shared library in win32?

[san hoi <hoisan49 gmail com>]

I try to build libdvw shared library. But following error occur.

https://live.gnome.org/Vala/SharedLibSample
http://gitorious.org/libdvw/libdvw

toddw TODDW-PC /C/msys/home/toddw/libdvw/dvw (master)
$ valac --pkg config --pkg gtk+-2.0 --pkg gee-1.0 --pkg libxml-2.0
--vapidir=../vapi/ *.vala --disable-warnings --library dvw-0.1

c:/msys/home/toddw/libdvw/dvw/util.vala.c: In function
`_vala_dvw_point_get_property':
c:/msys/home/toddw/libdvw/dvw/util.vala.c:586: warning: passing arg 2 of `g_valu
e_set_pointer' discards qualifiers from pointer target type
c:/msys/home/toddw/libdvw/dvw/util.vala.c:589: warning: passing arg 2 of `g_valu
e_set_pointer' discards qualifiers from pointer target type
c:/vala-0.12.0/lib/libmingw32.a(main.o):main.c:(.text+0xbd): undefined reference
 to `WinMain 16'
collect2: ld returned 1 exit status
error: cc exited with status 1
Compilation failed: 1 error(s), 0 warning(s)

I try to use Carl's 13.1 valac environment too. But it's a same result.
Thanks in advance for any suggetions.