[FieldTrip] define events for ft_definetrial

[Belluscio, Beth (NIH/NINDS) [E]]

HI all-
  I use CFT data sets in which I use a trigger channel to define various stimuli (usually called stim1, stim2, stim3).  Each stim repeats several times (120) during the data file.  The time points corresponding to each stim are catalogued in the MarkerFile.mrk file.  I would like to use these markers to define trials around each stim.  I used to do this with the following set of commands:
                cfg = [];
                cfg.dataset = 'TS1.ds';
                cfg.trialdef.eventtype = 'stim1';
                cfg.trialdef.prestim = 0.1;
                cfg.trialdef.posstim = 3.0;
                cfg = ft_definetrial(cfg)

Now when I do this I get the following error messages:
                readCTFds: Data set error:  size of meg4 files(s)
                                0 bytes (from dir command)
                                1126080000 (from res4 file)

                ??? Attempt to reference field of non-structure array.

                Error in ==> trialfun_general at 111
                For i=find(strcmp(cfg.trialdef.eventtype, {event.types}))

                Error in==> ft_definetrial at 126
                [trl, event] = feval(cfg.trialfun, cfg)

Is this a problem with the way I am defining the events?  How can I use these markers within the data file to specify events in fieldtrip?

Thanks,

Beth Belluscio MD-PhD
Clinical Fellow
Human Motor Control Section
NINDS, NIH
301-402-3495

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