Lokup Function help needed

Sample.xlsxHi all,

Need some help on a excel issue with Lookup (possibly not using right function right now but that is what we started with).

Workshet A, we have data in columns A - D and then a date in column E that is the due date, and then the columns that we want to determine are column F which we want the release date and column G the release number.

Worksheet B, we have column A with the release date and then column B with the release number.

We want the due date to be less than or equal to the release date. Examples:
due date of 04/01/13 we would want the first row in worksheet B with release date of 04/15/13 (col. F) and release number #1 (Col. G)
due date of 04/30/13 we would want the second row in worksheet B with release date of 05/15/13 (col. F) and release number #2 (Col. G)
due date of 05/16/13 we would want the third row in worksheet B with release date of 06/15/13 (col. F) and release number #3 (Col. G)


Right now we have this formula
=IFERROR(LOOKUP(DATEVALUE(A4),DATEVALUE(Releases!$A$2:$A$100),Releases!$B$2:$B$100),"Before First Listed Date")

but on a due date of 05/01/13 it is returning release date of 04/15/13 and release # of 1.

Any help would be greatly appreciated!! Thank you!!