Setting properties

I have tried limiting the scanner to only code 128 / ean 128 barcodes but doing the following on the page load event results in the scanner being enabled but not reading any codes.

        function enableScanners(){

             EB.Barcode.enable({'allDecoders': false,'code128ean128':true}, scanReceived);

        }

Am I doing something wrong.

It would be nice to see some more code examples as I"m sure I saw somewhere allDecoders used in conjunction with enabled rather than true.

Also tried this syntax

        function enableScanners(){

             EB.Barcode.enable({allDecoders:false,code128ean128:true}, scanReceived);

        }