[Serusers] ERROR: receive_msg: no mem for sip_msg

[Geniatakis Dimitrios]

When i am using in the configuration file 
modparam("usrloc", "db_mode", 1)
modparam("usrloc", "db_url","sql://root:hello@localhost/ser")
i get  ERROR: receive_msg: no mem for sip_msg
i am using ser 0.8.14  
when i use 
modparam("usrloc", "db_mode", 0)

there is not any problem in the server 
Could any one help???
Thanks