problem doing search/replace of question marks \?

[Arias Hung]

I'm having trouble replacing question marks that appear in a text file.  
Backslash escaping to literalize it doesn't seem to be working for me:

With a command like this:

:1,$s/\?//g

I get this error:

E64: \? follows nothing
E476: Invalid command

This is using version vim version 6.4.


If someone could take a moment to shed some light on this for me, it would be 
greatly appreciated.

Thanks in advanced.

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