Were the data entered in EpiData? If so, how could there be invalid dates? If the data were entered using another program you should still be able to validate the data with EpiData Entry, using a .chk file with a CONSISTENCYBLOCK and a CHECK command. In the Entry Help file use the Contents link to "Document datafile" and "Logical consistency check".
It's a good idea to clean up this type of error before using Analysis.
Jamie
Robert wrote
The function on Epidata that only allows valid dates is not allowing me to save data after the append command. The data entry keyers sometimes enter a wrong date. The invalid date does not become a problem (i believe) until I run the savedata command. Then the invalid date error pops up and the data is not saved.