[mono-android] How to use external dll in monodroid?

[mariano rotunno]

Hello,

i want to develop apps for Android using a machine visione software
library called HALCON,
it is a library that i already use in my vc++ and c# projects.
I've tried to simply add reference to my android app without "using
HalconDotNet" in the beginning of Activity1
in monodroid in vs2010, and after that to deploy the app with CTRL+F5 key,
but i get SIGNING FAILED: Could not sign the Android package. See
exception for more details.

i'm wondering if it is possible to use libraries like this in android...