Admin extensions modification page can not be loaded

Hey, I installed and modify few extensions , but now when I go to admin extensions modification page I get this message below , whats the reason ? and how to fix it ?

Fatal error: Uncaught Exception: Error: Could not load model extension/module/modification_manager! in /home/dickkbdx/buxstonesB1/storage/modification/system/engine/loader.php:89 Stack trace: #0 /home/dickkbdx/buxstonesB1/storage/modification/admin/controller/marketplace/modification.php(16): Loader->model('extension/modul...') #1 /home/dickkbdx/buxstonesB1/storage/modification/system/engine/action.php(79): ControllerMarketplaceModification->index() #2 /home/dickkbdx/buxstones.com/b1/admin/controller/startup/router.php(26): Action->execute(Object(Registry), Array) #3 /home/dickkbdx/buxstonesB1/storage/modification/system/engine/action.php(79): ControllerStartupRouter->index() #4 /home/dickkbdx/buxstonesB1/storage/modification/system/engine/router.php(80): Action->execute(Object(Registry)) #5 /home/dickkbdx/buxstonesB1/storage/modification/system/engine/router.php(69): Router->execute(Object(Action)) #6 /home/dickkbdx/buxstones.com/b1/system/framework.php(165): Router->dispatch(Object(Action), Object(Action)) #7 /home/dick in /home/dickkbdx/buxstonesB1/storage/modification/system/engine/loader.php on line 89


Thanks

1. Delete Ocmod cache using FTP or Cpanel-->File Manager
2. Login to Admin, go to Modifications and Disable Modification Manager, then refresh.