Slide simultaneously displaying 2 stimuli from 2 independant lists

[Christel Devue]

Dear E-prime users,

I'm trying to display a slide composed on each trial of a different face 
and of a pair of different numbers.
The faces have to be different in each trial and randomly appear on the 
right (half of them) or on the left (the other half). These faces have 
to appear in a particular sequential order. Regarding the numbers, there 
are 4 kinds of pairs and they have to appear in a random order.
The subject's task is to respond to numbers while ignoring the face.

Thus, the point is that one face and one pair of numbers have to appear 
on the screen AT THE SAME TIME (and same duration).
To do so, I have tried to make a list, let's say 'DisplaySlide List', 
with 2 Nested lines, to obtain a sublist for faces and another for numbers.
Then, I insert a Slide in the TrialProc (defined in the DisplaySlide 
list, and I've even tried it with a higher order additional list) 
appealing a face AND a pair of numbers from the two sublists. But it 
does not work.
When I try to run the experiment, I obtain an error message (saying that 
it cannot find one column refering to either a face or a number). 
Nevertheless, I know that there is no problem with each idenpendant 
sublist (because a made 2 scripts with each one in order to check, and 
each of them work as i want).

As I can understand, Nested Lists make the different items within the 
different lists appear sequentialy. So I think, this is not the good way 
to make the face and the numbers appear at the same time. But i do not 
know the right way to do it.
However, I think I had to make these two different lists for faces and 
for numbers because they have different particularities and have to be 
independant from each other.

So my question is: How can I present two kinds of stimuli controlled by 
two idenpendant lists at the same time?

Hope my question is not too messy. Thank you in advance for your help!
Best,

Christel Devue
University of Liege, Belgium