I have been having troubles with qdec and several error messages appear. The first message appeared when clicking 'analyze'. It doesn't matter if i use one or two discrete plus one or two continuos factors, i get the same error message. What does it mean by codno=1e+08? 

Creating output directory /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness

Loading y from /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/y.mgh

Matrix condition is 1e+08

ERROR: matrix is ill-conditioned or badly scaled, condno = 1e+08

Possible problem with experimental design:

Check for duplicate entries and/or lack of range of

continuous variables within a class.

Another error message that appeared earlier when i include age, gender, diagnosis(epilepsy/nonepileptic) and ln_postcentral_thickness is as follow:

$Id: mri_glmfit.c,v 1.138.2.3 2008/08/27 13:33:05 greve Exp $

cwd /Applications/freesurfer

cmdline mri_glmfit --y /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/y.mgh --fsgd /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/qdec.fsgd dods --glmdir /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness --surf fsaverage lh --label /Applications/freesurfer/subjects/fsaverage/label/lh.cortex.label --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Avg-Intercept-thickness.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Avg-thickness-age-Cor.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Avg-thickness-lh_postcentral_thickness-Cor.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Diff-Male-Female-Intercept-thickness.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Diff-Male-Female-Cor-thickness-age.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Diff-Male-Female-Cor-thickness-lh_postcentral_thickness.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Diff-nonepileptic-epilepsy-Intercept-thickness.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Diff-nonepileptic-epilepsy-Cor-thickness-age.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-Diff-nonepileptic-epilepsy-Cor-thickness-lh_postcentral_thickness.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-X-gender-diagnosis-Intercept-thickness.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thicknesss/contrasts/lh-X-gender-diagnosis-Cor-thickness-age.mat --C /Applications/freesurfer/subjects/qdec/lh_postcentral_thickness/contrasts/lh-X-gender-diagnosis-Cor-thickness-lh_postcentral_thickness.mat 

Can the above error occur because  one of the two groups has only one subject (epilepsy and female). I have also attached fsgd1 generated by freesurfer as below:

GroupDescriptorFile 1

Title lh_postcentral_thickness

MeasurementName thickness

Class genderMale-diagnosisnonepileptic

Class genderFemale-diagnosisnonepileptic

Class genderMale-diagnosisepilepsy

Class genderFemale-diagnosisepilepsy

Variables age lh_postcentral_thickness

Input RCoward genderMale-diagnosisnonepileptic 11.000000 2.112000

Input SCoward genderFemale-diagnosisnonepileptic 13.000000 1.979000

Input JConigrave genderMale-diagnosisnonepileptic 10.000000 2.470000

Input AConigrave genderFemale-diagnosisnonepileptic 5.000000 2.268000

Input KBleasel genderFemale-diagnosisnonepileptic 9.000000 2.292000

Input MBleasel genderFemale-diagnosisnonepileptic 16.000000 2.181000

Input CMcintosh genderFemale-diagnosisnonepileptic 15.000000 2.107000

Input OJohanssen genderMale-diagnosisnonepileptic 6.000000 2.033000

Input MJohanssen genderFemale-diagnosisnonepileptic 6.000000 2.037000

Input GHerbert genderFemale-diagnosisnonepileptic 4.000000 2.209000

Input JRathmell genderMale-diagnosisnonepileptic 11.000000 2.287000

Input ARathmell genderMale-diagnosisnonepileptic 14.000000 2.223000

Input ZTucker genderFemale-diagnosisepilepsy 11.000000 2.415000

Your advice and tips will be most appreciated!

            Toh Wong  (Sydney, Australia)