[horde] PHP claims MySQL isn't supported

[Thant Tessman]

I'm attempting to get IMP working. I'm close, but after logging in, it 
reports that the DB mysql extension isn't found. (The full text of the 
error message is appended below.)

Horde's test.php reports in the PHP Module Capabilities that MySQL isn't 
supported. But I have it installed and running, and I've gone through 
the setup instructions in horde/scripts/db/README without trouble. I've 
restarted everything more than once. The phpinfo screen reports that the 
configure script was called with '--with-mysql=shared,/usr'.

Why does PHP not know about MySQL? (I'm assuming that's the problem.) 
Any advice would be greatly appreciated.

-thant

RedHat 7.3
Horde 2.0
IMP 3.0
rpm mysql-3.23.49-3
rpm mysql-server-3.23.49-3

object(db_error)(7) {
  ["error_message_prefix"]=>
  string(0) ""
  ["mode"]=>
  int(1)
  ["level"]=>
  int(1024)
  ["code"]=>
  int(-25)
  ["message"]=>
  string(29) "DB Error: extension not found"
  ["userinfo"]=>
  array(6) {
    ["phptype"]=>
    string(5) "mysql"
    ["hostspec"]=>
    string(9) "localhost"
    ["username"]=>
    string(5) "horde"
    ["password"]=>
    string(8) "mypassword"
    ["database"]=>
    string(5) "horde"
    ["table"]=>
    string(11) "horde_prefs"
  }
  ["callback"]=>
  NULL
}
[/var/www/horde/lib/Prefs/sql.php : 102]