Firebug reports js error

I get an error with FCKEditor 2.6.5 and 2.6.4

syntax error
? in fckeditorcode_gecko.js@63()fckedi...ecko.js (line 63)
? in fckeditorcode_gecko.js@32()fckedi...ecko.js (line 32)
? in fckeditorcode_gecko.js@70()fckedi...ecko.js (line 70)
? in fckeditorcode_gecko.js@88()fckedi...ecko.js (line 88)
? in fckeditorcode_gecko.js@99()fckedi...ecko.js (line 99)
? in fckeditorcode_gecko.js@99()fckedi...ecko.js (line 99)
? in fckeditorcode_gecko.js@29()fckedi...ecko.js (line 29)
? in fckeditorcode_gecko.js@31()fckedi...ecko.js (line 31)
WaitForActive()fckedi...Default (line 259)
? in fckeditorcode_gecko.js@29()fckedi...ecko.js (line 29)
? in fckeditorcode_gecko.js@31()fckedi...ecko.js (line 31)
_FCK_EditingArea_OnLoad()fckedi...ecko.js (line 31)
? in fckeditorcode_gecko.js@36()fckedi...ecko.js (line 36)
[Break on this error] }\n

Any Ideas on the problem?

The editor is initialized with this code;

$oFCKeditor = new FCKeditor('introtext') ;
$oFCKeditor->BasePath = 'fckeditor/' ;
//$oFCKeditor->Config["CustomConfigurationsPath"] = "/myconfig.js"  ;

$oFCKeditor->Value = $Introtext ;
$oFCKeditor->Create() ;