Ribbon custom script strange error

I have avascript function in a specific WebResource

I have modified the Lead ribbon adding a button who run my custom function

If I click the button the function run well but when I close the form I get an error:

Microsoft Dynamics CRM Error Report Contents

<CrmScriptErrorReport>
  <ReportVersion>1.0</ReportVersion>
  <ScriptErrorDetails>
   <Message>Syntax error</Message>
   <Line>1</Line>
   <URL>/userdefined/edit.aspx?_gridType=4&etc=4&id=%7b<Entity Id>%7d&pagemode=iframe&preloadcache=<preloadcacheNumber>&rskey=<rskeyNumebr></URL>
   <PageURL>/userdefined/edit.aspx?_gridType=4&etc=4&id=%7b<Entity Id>%7d&pagemode=iframe&preloadcache=<preloadcacheNumber>&rskey=<rskeyNumebr></PageURL>
   <Function></Function>
   <CallStack>
   </CallStack>
  </ScriptErrorDetails>
  <ClientInformation>
   <BrowserUserAgent>Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; WOW64; Trident/6.0; .NET4.0E; .NET4.0C; InfoPath.3; .NET CLR 3.5.30729; .NET CLR 2.0.50727; .NET CLR 3.0.30729)</BrowserUserAgent>
   <BrowserLanguage>en-US</BrowserLanguage>
   <SystemLanguage>it-IT</SystemLanguage>
   <UserLanguage>it-IT</UserLanguage>
   <ScreenResolution>1366x768</ScreenResolution>
   <ClientName>Web</ClientName>
   <ClientTime>2013-06-27T12:24:04</ClientTime>
  </ClientInformation>
  <ServerInformation>
    <OrgLanguage>1033</OrgLanguage>
    <OrgCulture>1033</OrgCulture>
    <UserLanguage>1033</UserLanguage>
    <UserCulture>1033</UserCulture>
    <OrgID><Org ID></OrgID>
    <UserID><User ID></UserID>
    <CRMVersion>5.0.9690.3448</CRMVersion>
  </ServerInformation>
</CrmScriptErrorReport>

If I don't click my button no error was generated.

I have tried with a simple script (just alert('Hello world')) and I get the same error

If I debug with IE 10 Developer toolbar the debugger stop at the first character of the page

The only error I see is in the IE 10 Developer toolbar whit Network capture enable. The sistem do this get call:

Request GET /<OrgName>/userdefined/<Web Resource> HTTP/1.1

and receive this error:

Response HTTP/1.1 404 Not Found

But the <Web Resource> is correct and the script run and work!

Lso

LSo Lorenzo Soncini Trento TN - Italy