‘Not found’ msg on page when pasting javascript tag!

I want to use google site optimser, when I paste the javascript tag into the html box of my site https://www.fishingchair.org.uk/

I get this error:

Not Found
Sorry, but you are looking for something that isn’t here

I am redirected to this page:
https://www.fishingchair.org.uk/wp-admin/page.php

In reading I have the static page selected with the relevant page as the front page, I also encountered this error when copying & pasting normal text from the text file.

This is the javascript code:
<!– Google Website Optimizer Control Script –>
<script>
function utmx_section(){}function utmx(){}
(function(){var k=’2215425254′,d=document,l=d.location,c=d.cookie;function f(n){
if(c){var i=c.indexOf(n+’=’);if(i>-1){var j=c.indexOf(‘;’,i);return c.substring(i+n.
length+1,j<0?c.length:j)}}}var x=f(‘__utmx’),xx=f(‘__utmxx’),h=l.hash;
d.write(‘<sc’+’ript src=”‘+
‘http’+(l.protocol==’https:’?’s://ssl’:’://www’)+’.google-analytics.com’
+’/siteopt.js?v=1&utmxkey=’+k+’&utmx=’+(x?x:”)+’&utmxx=’+(xx?xx:”)+’&utmxtime=’
+new Date().valueOf()+(h?’&utmxhash=’+escape(h.substr(1)):”)+
‘” type=”text/javascript” charset=”utf-8″></sc’+’ript>’)})();
</script>
<!– End of Google Website Optimizer Control Script –>