Set Range Of Cells To Ensure They Are Completed Before File Saved

I keep getting a "type mismatch error" for this:

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)

If Len(Range("E18:E34")) = 0 Then
MsgBox "You must complete cell E18 thru E34 before you can save this file!"
Cencel = True
End If

I am trying to set a range of cells to ensure they are completed before the file can be saved. I can get it to work with individual cells, but not when I use multiple cells like in the example above.

This Works fine:

If Len(Range("D5")) = 0 Then
MsgBox "You must enter the Impress Amount before you can save this file!"
Cancel = True
End If