Thank you for your answer. Look what i did. I emptied the log file and then i tried to make subscribers as test a couple of times. I checked again the log file and this is the error.
27-03-2013 12:00:21 – ERROR – 46239896 – save: Unknown column ‘followup’ in ‘field list’
27-03-2013 12:00:45 – ERROR – 46240024 – save: Unknown column ‘followup’ in ‘field list’
27-03-2013 12:18:04 – ERROR – 46241552 – save: Unknown column ‘followup’ in ‘field list’
27-03-2013 22:15:07 – ERROR – 46233848 – save: Unknown column ‘followup’ in ‘field list’
27-03-2013 22:17:02 – ERROR – 46236736 – save: Unknown column ‘followup’ in ‘field list’
27-03-2013 22:21:06 – ERROR – 46233904 – save: Unknown column ‘followup’ in ‘field list’
27-03-2013 22:21:13 – ERROR – 46233896 – save: Unknown column ‘followup’ in ‘field list’
Later edit : also the follow up is set to NO.