[NEST Users] About the spike_detector records

Dear all, Recently I always have an error when I tried to keep the spike_detector information into files. ********************** Nov 18 19:22:09 RecordingDevice::calibrate() [Error]: I/O error while opening file '0-94476-15.gdf'. This may be caused by too many open files in networks with many recording devices and threads. ********************** And I also found most of the gdf files are empty. Do you have any idea to solve this issue? And do you know how to avoid to keeping empty gdf files. Best wishes Sun