I have a NFC door that unlocks with tags, I can scan the tags with my phone and even copy my spark 2 to the tags. But I can’t get my chip to program into the door. Any ideas what would cause this
sooo… yeah… somewhere on this forum (ok many places) i complain that software developers are lazy 
in short, the ISO14443A protocol standard should allow any ISO14443A reader to get the UIDs of any and all reporting transponders in the field without even needing to select them (which silences all other transponders in the field)… however, when it comes to reader firmwares and application softwares used with these reader chips, more often than not the UID is not observed from this standard ISO14443A interaction between transponder and tag, but through some other means… possibly memory inquiry or some other activity that occurs later on in the ISO14443A communication flow, after chip select has been issued.
The problem with this is that approach is that it throws out compatibility with all ISO14443A transponders and narrows in on a specific chip type selected for that application. Some costing person or engineer decides “our lock with will work THIS chip specifically” and then they just program to support that chip and nothing else… why would they care if it’s not part of the door lock spec or a marketing goal?
On top of that possibility is the possibility that the software at various levels is receiving the UID of your Spark 2 just fine, but the “enrollment” process is expecting some shitty 4 byte Mifare Classic NUID and you present a 7 byte ID… it borks out and just rejects it outright. This is why on a Samsung Ezon door lock with firmware specific to the Mifare Classic, you can present your Spark 2 during an unlock attempt and it just beeps “bad tag” at you… it is reading it just fine… but when you try to enroll it, you can’t because the firmware is shit or specifically made to reject all but Mifare Classic 4 byte NUIDs (like the included keychains use).
Ultimately I hate this, but usually there is little to no way to fix it in existing hardware. Sometimes if you are talking about a commercial access control system you can tweak the “chip types” recognized by the system… usually some obtuse esoteric method that even the people running the system probably don’t realize it can do… but for the most part, with stand alone or consumer door locks you are SOL.
Amal answered this above 
Could you tell us the make and model, plus photos if possible and a shared TagInfo scan
If you provide that info I asked for above, there may be some options / possibilities / suggestions we can give you