No title

Dears,
When i wanna insert to my following code,I receive following error:
Insert into c(t) values('ccccccc'); --> It's my qurey.
Insert command failed!So i can't continue to insert in your table!
ERROR: pg_atoi: error in "ccccccc": can't parse "ccccccc"

my code :
pres = PQexec(pobj->connection2db, ins.c_str());
ins="";
if (!pres || PQresultStatus(pres) != PGRES_COMMAND_OK)
{
fprintf(stderr, "Insert command failed!So i can't continue to insert
in your table!\n");
cout << PQerrorMessage(pobj->connection2db);
pobj->exit_nicely(pobj->connection2db);
}
PQclear(pres);

When i print ins.c_str(),I see following statement:
Insert into z(e) values('10z');
It's true,But i recieve same error.
Please help me..............
--Mohsen