JavaScript Error on Search

When I enter a value to Search for on the Search page of my WWF, I get the following Java error:

Java Script Error
Description:'document.frmSearch.KW.value' is null or not an object
Source:search_forum.asp?FID=5
Line:18

See More Details?
Ok / Cancel

Whether I hit Ok or Cancel, the search runs, and gives valid results, so I know the keyword value is being passed and the search itself is running, so why am I getting the eorror?

Hmm. As far as I know, nothing has been modified in the search.asp and search_forum.asp files themselves.  The frmSearch exists and works.  I have another search that appears in the header, but it has a different name than the WWF one.  And the forum is new install, not an upgrade.

Ok. I copied and pasted the CheckForum javascript function from this forum's forum_search.asp page into mine, and that fixed it. 

Thanks for your help!