afni.nimh.nih.gov

When attempting to perform the 3dcalc function:

3dcalc -prefix file -session dir1/dif2 -a 'scan1+orig[5..100]' -expr 'a'

I receive the error:

ERROR: selector index 5 is out of range 0..0

What does this mean exactly and how do I resolve it? I interpret it to mean that my TR range is out of the range of the file, but also think there must be some other issue because I'm quite sure my TR range is correct.

Thanks...