Get Date From The Filename

I have a filename 'filename-12-14-2014' where i need to extract date information from the filename and insert a new heading in the file 'date' in the first column and write the extracted date till the end (until data exists). I can write the new column name but i could not write date in all the fields. code i wrote is below

this is for extracting date from the filename. the 4th lines throws me the error?

(1) LastRow = Cells.Find("*", SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
(2) With Range("A2:A" & LastRow)
(3) x = Split(s, "- ", 2)
(4) .Value = Left(Mid(x(1), InStr(x(1), "-") + 1), InStr(Mid(x(1), InStr(x(1), "-") + 1), ".") - 1)
(5) .NumberFormat = "mm/dd/yy"

for adding the date in the first column. This works fine

Columns("A:A").Select
Selection.Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
Range("A1").Select
ActiveCell.FormulaR1C1 = "Date"
s = ActiveWorkbook.Name
Range("A2").Select