Symbols in Microsoft Word

[Michel Treisman]

In Microsoft Word 2004  one can type
  === Return
  and Word converts it into double lines across the page.  Except that 
has stopped working for me.   When I type ===  or  ---  nothing 
happens.

Under     Tools>Autopcorrect>autoformat as you type,    I have checked
  Replace as you type
	Symbol characters with symbols

But it doesn't work.  What should I try next?

Mike