Help me on this WEBI error

Hi Team,

While opening Webi report its taking long time, and am getting following error

"while trying to invoke the method com.sap.sl.dictionary.DirectoryExpressing.getID() of a null object returned from com.businessobjects.rebean.wi.model.reportspec.IDictionaryExpressionFilter.getExpression()"

Please find the attachment and help me on this ASAP.

Thanks,

tulasi.