Hello, 
I have several studies displaying multiple equivalent contrasts of interest (for ex Study 1a and Study1b) so I want combine them to have one contrast of interest per study, taking account dependency btw the different contrasts within a study (resulting in Study 1). 

So I pre-processed Study1a and Study1b. Then I have understand that I must combine these two. So I clicked on "combine images" and I tried to combine 4 files: t_upper study 1a, t_upper study 1b, t_lower study 1a, t_lower study 1b. Am I right ?
It created a var_reduced file with only the number "1" inside, so I suppose that I miss something...

Someone could help me please ?

Thanks !!
Layla