Replace Values in Headers

Hello All,

  I'm creating a function that will cleanse and model a monthly invoice that we receive. The problem with this invoice is that some months the headers have underscores between the words (ie. Order_Number, Date_Created), but other months the underscore is not used. I'd like to remove the underscores the way that one might use Replace Values. I tried transposing the data so that I had all of the headers in one column, used the Replace Values function

= Table.ReplaceValue(#"Transposed Table","_"," ",Replacer.ReplaceValue,{"Column1"})

 but nothing happened! It didn't remove any of the underscores. I tried a longer string of characters (one that is absolutely in that column) and it just doesn't work. 

Any suggestions?

Thanks