TypeError while using packet_sink

Hey,
I am trying to incorporate a packet_sink into my project and
everytime
i do so, i receive the following error message :

TypeError : in method ‘packet_sink’, argument 1 of type
‘std::vector<unsigned char, std::allocator> const &’ ,
and
i am trying to draw the default_access_code mentioned in the
packet_utils
module which is a string of 1’s and 0’s . What kind of type cast does it
require then ? I find myself slightly confused .

Any help would be deeply appreciated.

Thanks,
Anay.