SPI postgresql - insert data into table from postgres.c

Question

I'm working inside postgres.c (inside exexc_simple_query) of postgresql 9.1 (line 1094 of http://doxygen.postgresql.org/postgres_8c_source.html#l00829 ). I need to insert some query information in a table that I will check in a second moment. I'm trying to do it with SPI using these three lines:

SPI_connect();
SPI_exec("INSERT INTO testvalues (11,6)", 5);
SPI_finish();

but when I start the server and I send a query I get segmentation fault:

LOG:  server process (PID 13856) was terminated by signal 11: Segmentation fault
LOG:  terminating any other active server processes
WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:  In a moment you should be able to reconnect to the database and repeat your command.
FATAL:  the database system is in recovery mode
LOG:  all server processes terminated; reinitializing
LOG:  database system was interrupted; last known up at 2013-07-14 00:40:22 CEST
LOG:  database system was not properly shut down; automatic recovery in progress
LOG:  record with zero length at 0/17D7368
LOG:  redo is not required
LOG:  autovacuum launcher started
LOG:  database system is ready to accept connections

Do you have any idea how I can fix it? Is there a better way to insert data from the postgres.c?