I am Newbie to NFC Android App Development. I am done with the App development and everything worked fine. As part of my testing I used MifareClassic as well MifareDesfire tags to write and read. I am storing data in Ndef format. Initially I used the above testing tags with other apps like Nxp tagwriter and Tagstand Tagwriter and then I used with My app. So everything worked fine. Even later I used my app to write and read data from Sony Felica tags(new tags) which also worked fine. So I passed app to client for review but I came to know that app is not writing on New Tags. If they are reset from other apps then It works fine. So I done the same test here and found the same issue as client reported. What might be the issue? Has someone come across same kind of issue? Is it required to format before using? if so how to do that? Someone Help to solve the issue. Thanks in Advance.