I am new to SPM, and am running it on a Leopard iMac with all updates installed to date.

  Slice timing works fine with one session (any of the 3) input, but if I put in more than 1 (e.g., the 
three runs for the subject), it gives me this error:

Running "Slice Timing"

SPM5: spm_slice_timing (v$Rev: 671 $)              10:00:10 - 18/07/2008
Your TR is 3.0

Error running job: Error using ==> minus
Matrix dimensions must agree.
In file "/Users/MLE/Desktop/SPM_Stuff/spm5/spm_slice_timing.m" (v671), function 
"spm_slice_timing" at line 208.
In file "/Users/MLE/Desktop/SPM_Stuff/spm5/spm_config_slice_timing.m" (v1032), function 
"slicetiming" at line 170.

Am I doing something wrong?

Thank you,