navigational keys in protected sheets
 

I have two sheets in the same purchase order workbook. Second sheet is same
as first with some additional cells locked. The navigational keys work fine
when the sheets are unprotected. When I protect the two sheets, the keys
continue to work fine on the first sheet. But on the second page the tab and
left/right arrows will only work within the same row and will not go to next
cell in next row. The Enter and up/down arrows do not work at all. The area
that I'm working with is identical in both sheets. To input data on the
second sheet, you have to keep using the mouse to go to the needed cell in
each row. Why does one sheet work and the next doesn't?