Hi All - this post is fairly old, but I recently discovered that this error often relates to the Payroll Control Record (TCODE: PA03).
Lets say the payroll period is set to 41.2012.
If you try to do a delta containing data from week 40.2012 - 44.2012 you'll get this error for the first record in week 40.2012.
The fix is to just change the Payroll period in Pa03 to 40.2012.
Similar you might observe that you get incomplete data when trying to do a delta init, which is caused by the same setting. Full loads steps outside this lock, so if you compare number of records from a full load with a delta init you might observe that the full load contains more records, which indicates that the payroll period in pa03 is not set correctly.
Hope this helps some of you googlers like myself 
BR
Jess