“next page” no longer shows since upgrade

Recently upgraded from an older version on several blogs. All went fine but for one. The “next page” link no longer shows on any theme. I thought it was my custom theme but tried the default theme and it won’t show there, either.

Can someone please tell me what changed so I can fix it?

On category pages, it shows, but previous page does not … and they are reversed, of course (most templates have the code reversed for some odd reason).