It is generally safer with dates and filters to convert to numeric values - for example:
Code:
.AutoFilter Field:=12, Criteria1:=">=" & CDbl(STARTDATE), operator:=xlAnd, criteria2:="<=" & CDbl(STARTDATE)
This assumes that STARTDATE is a Date type variable. If not, you can convert that using CDate like this:
Code:
.AutoFilter Field:=12, Criteria1:=">=" & CDbl(CDate(STARTDATE)), operator:=xlAnd, criteria2:="<=" & CDbl(CDate(STARTDATE))