Dear SPMers:

I met one problem when conducting PPI analysis. 

At the very last step of PPI analysis (after all single subjects' contrast for the PPI regressor was calculated), I performed a second level analysis by calculating a one-sample t  test on the single-subject contrast coefficients (12 subjects in total). 

However, there comes out a warning message as: "There are no significant voxels, The globals are plotted for diagnosis", and the error message in SPM was "??? Error using ==> plot 

Vectors must be the same lengths.

Error in ==> spm_spm at 812

        plot(SPM.xGX.rg)

Error in ==> spm_getSPM at 210

		[SPM] = spm_spm(SPM);

Error in ==> spm_results_ui at 264

[SPM,xSPM] = spm_getSPM;

??? Error using ==> [hReg,xSPM,SPM] = spm_results_ui;

Error using ==> plot

Vectors must be the same lengths.

??? Error while evaluating uicontrol Callback"

Interestingly, if I excluded one subject's data, there was no such problem.