Reg:lo_open error..pls help me

Is it possible to use lo_open after creating the object while the application is running?
Hi,
In my application i need to create a file dynamically and load it into DB.

So.....I have created one object at run time .....and trying to open it inorder to write the content into it.....
But lo_open is returning -1(-ve value).
where i am doing mistake pls tell me.

lobjId = lo_creat(conn, INV_READ | INV_WRITE);
if (lobjId == 0)
fprintf(stderr, "can't create large object\n");

lobj_fd = lo_open(conn, lobjId, INV_WRITE);
//My application failed at this point..what i am missing here ?
if (lobj_fd < 0)
{
fprintf(stderr, "can't open large object %d\n",lobjId);
}
lo_lseek(conn, lobj_fd, 0, SEEK_SET);
nwritten = 0;
len = strlen(szContent);
while (len - nwritten > 0)
{
nbytes = lo_write(conn, lobj_fd, szContent, len - nwritten);
nwritten += nbytes;
}