Hi and welcome everyone

I am having problem with CS4070. My company has bought a couple of those, for ticket check-ins at events we are organizing.
My task is to write an Android app for those scanners.
I did manage to get the scanning functionality working (despite outdated PDF / YouTube guides), but commanding LED is driving me nuts.
No matter how I approach this issue, LED will just not work. Bepper works just fine, but whenever I use opcode for controlling LED, scanner freezes: no scan is returned an no beep.

I use following code:
    private void performOpcodeSetAction(int codeValue) {        String inXML = prepareInXML(codeValue);        int scannerID = connectedScannerID; //getIntent().getIntExtra(Constants.SCANNER_ID, -1);        if (scannerID != -1) {            StringBuilder outXML = new StringBuilder();//            sdkHandler.dcssdkExecuteCommandOpCodeInXMLForScanner(DCSSDKDefs.DCSSDK_COMMAND_OPCODE.DCSSDK_SET_ACTION,inXML,outXML,connectedScannerID);            new MyAsyncTask(scannerID, DCSSDKDefs.DCSSDK_COMMAND_OPCODE.DCSSDK_SET_ACTION,sdkHandler,outXML).execute(inXML);        } else {            Toast.makeText(this, R.string.scanner_invalid, Toast.LENGTH_SHORT).show();        }        Log.i(TAG, "OPCODE SET_ACTION : " + codeValue);    }    private String prepareInXML(int value){        return "" +                    "" + connectedScannerID + "" +                    "" +                        "" + value +"" +                    "" +                "";    }
and then, I call the action by just supplying proper opcode:

performOpcodeSetAction(17); //low long beep
and that works.

BUT...

when I try to add LED control, like:
        performOpcodeSetAction(47);// red LED on        performOpcodeSetAction(17);// low long beep        performOpcodeSetAction(48);// red LED offscanner toggles amber LED and freezes.

I have also tried following:
private String prepareInXML(){    return "" +                "" + connectedScannerID + "" +                "" +                    "47,17,48" +                "" +            "";}
and with semicolons:
private String prepareInXML(){    return "" +                "" + connectedScannerID + "" +                "" +                    "47;17;48" +                "" +            "";}
also with arguments split:
private String prepareInXML(){    return "" +                "" + connectedScannerID + "" +                "" +                    "47" +                    "17" +                    "48" +                "" +            "";}
none of the above worked.
Android devices, I am using are on API 22 (android version 5.1)
scanners have been updated with latest firmware (although, scanning the firmware version barcode returns old version number)

What am I doing wrong? Anyone kind enough to help me out on this one?