I try to add the lpsolve extension to php but something is not working. Here are all the steps I I made when I installed it. 1.I installed wamp server in C 2.I copied php_phplpsolve55.dll from www.peno.be/lp_solve/PHP/5.3/ and I put it in the folder specified by php.ini extension_dir = "c:/wamp/bin/php/php5.3.0/ext/" 3. I added the extension here ;extension=php_shmop.dll ;extension=php_snmp.dll ;extension=php_soap.dll ;extension=php_sockets.dll ;extension=php_sqlite.dll ;extension=php_sqlite3.dll ;extension=php_sybase_ct.dll ;extension=php_tidy.dll ;extension=php_xmlrpc.dll ;extension=php_xsl.dll ;extension=php_zip.dll extension=php_phplpsolve55.dll ;;;;;;;;;;;;;;;;;;; ; Module Settings ; 4.I copied from lp_solve_5.5.2.0_dev_win32 the lpsolve dll file and I put it in the System32 folder. 5.I restarted all services I run a test file and gives me this error: Warning: include(lp_solve.php) [function.include]: failed to open stream: No such file or directory in C:\wamp\www\proiecte\ex.php on line 5 Warning: include() [function.include]: Failed opening 'lp_solve.php' for inclusion (include_path='.;C:\php5\pear') in C:\wamp\www\proiecte\ex.php on line 5 Fatal error: Call to undefined function lp_solve() in C:\wamp\www\proiecte\ex.php on line 14 When I open localhost with the wamp aplication I see the lpsolver extension there and it says that is loaded. I even uninstalled wamp and I installed php directly but it still doesn't work. So I do not know what else to do