asterisk users - Jan 2016 - Asterisk 13.7.0 failed to start - PJSIP 2.4.5

Hello,

We installed the subject detailed versions on a uptodate debian wheezy. 
When starting Asterisk we get

  Loading chan_pjsip.so.
   == Registered RTP glue 'PJSIP'
   == Registered channel type 'PJSIP' (PJSIP Channel Driver)
18:26:10.812 sip_endpoint.c !Module "mod-refer" registered
asterisk: ../src/pjsip-simple/evsub.c:417: pjsip_evsub_register_pkg: 
Assertion `mod_evsub.mod.id != -1' failed.

Any clue on what could be the problem ?

Thanks

-- 
Daniel