Simultaneous trills?

[pianist7]

I can play trills going in opposite directions, like 2323
                                                                  2323
but not 2323
          3232
Any help? I've been playing for nine years, and I should be able to do this

[gyzzzmo]

Practise slowly and gain speed. And always focus (with help of rhythm) on your weakest hand.

[point of grace]

with the exact pulse in your head!

[pianist7]

so how long should I practise, whether with or without the piano?

[birba]

And in what music do you find this little gem?

[pianist7]

many pieces, including second mvts of Grieg and Rach 2 concerti

[birba]

In the grieg, if you're referring to the last measures of the second movement, I think you're going about it wrong.  First of all, I would play them both with 1-3 and a very fast shaking rotation of the forearm.  And who's counting or noticing the simultaneous "coincidence" of the individual notes of the trills?!

[pianist7]

my ears hurt otherwise