Your gears are synchronized by what are called synchros. If you match the rpms to the transmission correctly you could shift without using the clutch. This is how most transmissions in semis work. If the rpms are not meshed up correctly the transmission will grind. Since most people would have...
all you have to do is pour a couple teaspoons of sugar into the gas tank, and then let the car run until it turns itself off and presto, problem solved!
First off, the first person that answered your question gave you a clueless irrelevant answer, but to answer your question, it sounds like you have a bad cable, replace the cable or call the cable company, the prob could be on there end.