Just started tonguing...having some problems

i'm a clarinet player and i've been playing the clarinet for 3 years this is my fourth. i found out this year in my first year in high school that i haven't been tonguing correctly . what i was doing was blowing air through my instrument while resting my tongue on the reed (wierd i know). Now i've been practicing the right technique saying "ta" and using the tip of my tongue. My problem is tonguing the higher notes above middle C. I'll play whichever note w/o tonguing but when i begin to tongue i'll squeak or my air will sound fuzzy when it didn't at the lower notes. any thoughts as to what may be wrong?

Make sure that your not leaving your tounge in too long, or too much of it, also practise? As I get higher its easier to just slur to the next note, so just practsise scales with tounging
hopefully this helps!

Actually yes it does i'm seeing improvement from the problem becuase my tongue had been touching too long, thank you and practicing this will help!

Make sure not to hit the reed too hard either, or hit your tounge downward.

how can you tell if your touching the reed to light though?

Considering that you have been playing for quite a while, I would suggest that you take a look at your tongue while tonguing(without an instrument in your mouth of course) to ensure that you are moving your tongue upward and downward not in and out.

Moving your tongue in and out will cause a delay in response time(the note will take a while to sound) also it is more inconsistent(although I have known people who can do it quite consistently). Also try to minimize movement of the tongue while tonguing.Saying any syllable will do(ta to tu du da...) this is more to do with the style of articulation required by the music or the conductor.

Guys, what is tonguing for?