Unknown RFID tag

I have an unknown RFID tag and try to read Its value. I bought two readers RDM6300 125KHZ and RC522 13.56MHz. Each of the readers connected to arduino works well with the purchased corresponding tags, but none with this tag. According to my informations the tag should be 125kHz tag, but RDM6300 not read it. The tag is simply not detect. I am sure, that the tag works, I use it to open the door.

So my question is: Is there any other RFID reader for Arduino, which is different than the two that I have, and could work?

Thank you

Maybe the tag is not 125 kHz.

If the tag is not 125kHZ and not 13.56Mhz, so what else could it be?


Edit: even if the frequency does happen to match one of your readers, the data protocol could be different.