c# - Azure - TypeInitialization error -

i'm getting following type initialization error when call azure mobileservice client:

system.typeinitializationexception: exception thrown type initializer  microsoft.windowsazure.mobileservices.mobileserviceclient  ---> system.invalidprogramexception: invalid il code in system.net.http.httpmethod:get_post (): method body empty. @ microsoft.windowsazure.mobileservices.mobileserviceclient..cctor () [0x00000] in <filename unknown>:0   --- end of inner exception stack trace ---   @ rpitemp.program.main (system.string[] args) [0x00000] in <filename unknown>:0  

in years of programming, i've never seen "invalid il code" exception

i'm calling this:

           mobileserviceclient mobileservice = new mobileserviceclient("https://<removed>.azure-mobile.net/", "<keyhere>"); 

what's issue? code run using mono on raspberry pi.