The PNR (reservation code) used by the airline is different from that used by Sabre, etc - it's a pain. If you booked directly with the airline, I don't think you'll be able to use them. I always have a sabre PNR of something like BJJRTZ and a QF PNR of something like ZEIG2M.
QF PNRs are Amadeus linked (hence Checkmytrip) I don't know about DJ. Even with checkmy trip I find they give me 2 PNRs. I am no expert in these things. Hope others can help.
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