What is wrong if you have trouble shifting into all gears on a manual hydraulic clutch?

According to www.ehow.com this problem can be caused by your clutch reservoir being empty of brake fluid. The whole article is here: http://www.ehow.com/how_7677_check-fluid-hydraulic.html Hope this helps It may also be a symptom of a bad clutch master cylinder or clutch slave cylinder-- or perhaps a leaking hose or connection. Whatever the case, the primary cause is the fact that the hydraulic pressure is not building enough to disengage the clutch fully. I always start with the simple solutions first-- check the fluid levels and check thoroughly for any leaks--then bleed the clutch hydraulic system-- if that doesn't improve performance then I'd replace the master AND the slave cylinder and rebleed the system. That should get you shifting smoothly again.