Did you design the RFID reader yourself? If so the following questions apply.

-Do you have a data sheet for the tag IC?
-Do you have a data sheet for the tag?
-Do you know "desired" modulation scheme for the tag -ie, AM, FM, PWM, PMD or other?
-Do you know the "encoding scheme" for the tag -ie NRZ, RNZ, BiPhase, Manchester or other
-Is the tag 1/2 duplex (HDX) or full duplex (FDX) or a combination of both?
-Do you know the data protocol for the tag.... eg.. 101010 preamble, data then checksum etc?
-Do you know what the "tuned" frequency is for the tag?
-How do you know the frequency of the u2270 is the same resonant frequency of the tag
-How do know the u2270 coil antenna is tune to the correct frequency of the tag?
-Can you measure the RF field with a little RF coil connected to a CRO coming from the reader (to prove there is RF energy coming from the reader?)
-When the tag is in the RFID field and sitting on the reader can you seen the modulation modulating on the RF field using a little RF coil connected to a CRO?
- Can you see the demodulated data from detector demodulator of the u2270

If you can answer some of these questions then you are well on your way to debugging "your own project".

Joe