When I tryed to open the locked gate, I can move the hammers, but I can not get the sliders to move. Even when I followed the walkthrough instructions.

Try reinstalling Revelation from a clean boot, as detailed under Installing and Re-Installing Revelation, "8. Clean-boot Revelation Re-install, Previous Installation" in Myst IV: Clean Boot Install/Re-install With Win XP. Be certain to also read "1. Preventing Installation Problems - General Comments" under Installing and Re-Installing Revelation. And also doing the first 5 steps under Overall Windows and Hard Disk Tune-up before re-installing is a really good idea.