VBA to hide columns based on input date range

Hi Bernie.

This unfortunately doesn't seem to work. When i run the macro over the sheet it hides all the columns immediately.

Some more information:
- the format for row 17 is custom "mmm yy" with the first cell being 1/7/2008 and the =EDATE+1 formula carried across from there (if that makes any difference?)
- I need the columns to unhide when the range is changed (unsure if this makes a difference to your code)
- unsure if it will matter if the date range is say 1/7/12 to 30/6/13 given the second date isn't on the first of the month (as is the case with row 17)

Thanks.