Thanks for answer.
I've replaced all the literals by labels.
Set exportOnlyData to false
unfortunately I got a JS error and no csv file :( :
Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; InfoPath.3; .NET CLR 3.5.30729; .NET CLR 3.0.30729; MS-RTC LM 8; .NET4.0C; .NET4.0E)
Timestamp: Mon, 30 Aug 2010 15:34:51 UTC
Message: 'this.ColGroup.Cols' is null or not an object
Line: 3838
Char: 1
Code: 0
URI: http://serverurl/Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_PlaceHolderMain_boconges_radscript_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bTelerik.Web.UI%2c+Version%3d2010.1.519.35%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3afr-FR%3afcd44c12-f50d-4937-b05d-1aa46b5c5b3e%3a24ee1bba%3a1e771326%3a2bef5fcc%3a58366029%3aaa288e2d