gd for php5 under RH ES4

I am trying to use the php gd library (for imagecreate, etc) with php5 under Red Hat ES4. I tried installing php-gd via webmin (which in turn, I see, uses up2date), but get the following error in the apache error log when restarting: PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php4/gd.so' - /usr/lib/php4/gd.so: undefined symbol: empty_string in Unknown on line 0 I don't know if the problem is that php-gd is a php4 library or there is something else that I need to install or do. I saw something about php5-gd, but webmin/up2date can't find anything by this name. I have searched for a bit on this without joy; any guidance is appreciated. I am not a system administrator by training, but am a longtime Unix programmer, so I can handle reasonably low level instructions, if necessary. I did post this to a Red Hat list without any reply so far. Thanks in advance, Doug