Replace With feature error in Adobe XI Pro

Hi,

I get the following error when trying to use the Replace With feature: "Unable to highlight text across multiple text boxes."

I'm attempting to replace one term with another throughout a 38-page text document.

I'm new to XI Pro, so maybe there's a setting I need to make, but I'm not sure. As a copy editor, the main reason I wanted to use XI was for this search and replace feature. If anyone has any ideas, I'd appreciate the help.

Thanks!