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I've only seen this occur once before for one subject andI don't know why it occurred. 

It turns out the the contrast vector SPM.xCon.c does not get changed (please double check this in your case) and the fields that do get changed do not impact the contrast or T-test values. While its good to be concerned about odd warning messages like this one, this warning doesn't seem to impact the processing streams.

Perhaps one of the SPM authors could provide more details on why this happens for some models.

Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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On Fri, Mar 6, 2015 at 4:36 AM, gj <[log in to unmask]> wrote:
Hi,

I'm trying to use Donald Mclaren's nifty gPPI toolbox/PPPI v.13 and although for one contrast in particular, I first get a message saying "Valid contrast," this is followed by the warning:

---
c is not a proper contrast in +c->Tsp in spm_SpUtil
!!! projecting...
---

I see that spm_SpUtil.m returns a vector that reweights where the condition occurs in the different sessions and includes an additional small weight for one of the session constants. I guess this has something to do with orthogonality, but would appreciate if someone could explain to me when this happens, how/why the reweighting happens the way it does, and whether this warning is a big warning or one to just take under advisement.

Thanks for any clarification!
g