my jumping... problem? help appreciated

[A_Munk3y]

hey guys.... im new here. anyway
i used to be a dominant one-leg jumper but ever since my knee started hurting its changed...
my single leg jump hasnt changed at all...i can barely grab rim both hands when i single-leg jump, and its been like that for about 6 months....
and when i used to double leg jump i could barelytouch halfway up the net
now its opposite
i stand under the rim and take one step backthen i take one step forward and double leg jump and i can easily grab rim both hands

BUT my main problem is i cant double leg jump when running
if DBL leg jumping when running (what i normally do when i single leg jump)
i can barely touch rim with both hands
what am i doing wrong
some1 please help me
ive checked on the forum and i couldnt find anything about this

also if im a dominant left leg jumper when i jump with both legs which foot goes in front? and which foot goes down first ^^?
sorry for all the questions

[The Main Event]

Try to practice either foot in front for versatility. as for the running 2 foot jump just watch vince carter footage and study his technique. i did that and now i can almost CONSISTENTLY dunk off 2 feet. (1foot takeoff is much easier for me though)