Trouble with shoto combo

I’m trying to do the standard combo for shotos and I got most of it. The only part I need help with is the dp + RH and everything after. As soon as I do the second palm, I try to do the dp + RH. It either whiffs or hits only once. Then I can’t follow it up with dp + lp so I need some tips on why this happens and how i can fix it.

you’re not doing the rest of the combo fast enough i had this problem when i first started you want the dp rh to just inside of genei jin

This juggle had me practicing for a couple of days.
After your jab, short, strong chain and while in the jin never let go of foward. Making sure that the shoto body isn’t far down below especially in this situation in the corner. If the body begins to drop low your reacation time is going to have to be quicker, while your doing the F. Foward, F. Foward, Palm, F. Foward, F.Foward Palm ( this is when you should continue holding foward, do not let go and in one smooth dragon punch motion up kicks with roundhouse). From their it’s simple to finish it with a Jab shoulder, f. fierce and into lunge.