Thank you, But i think i am missing something fundamental here. Can anyone please confirm that the follow i'm trying out makes sense. i wish to run a Randomise analysis for a group of 32 participants with 2 runs each. First level i run FEAT for each individual run with the basic conditions i wish to contrast in the group level. Next i run a higher level analysis averaging the runs per participants, yielding 7 cope directories per participants. In order to run Randomise i need to convert the 3d cope images to one 4d file, for that i need to use fslmerge, only that this part doesn't work :) what am i doing wrong? Thank you, Navot