As stated above we need more information to even GUESS what is happening.
1) Where are you trying and what ALT are you trying for?
2) What does the Facilities Map for the location you're tying indicate as approved Alt in the sector you're trying?
Keep in mind that any location CAN get denied even in areas and alts there were previously "Approved". Airport and Airspace operations are very fluid/dynamic and circumstances can change to cause a DENIAL. Traffic Patterns can change (maintenance, damage, etc), Traffic can become congested (Military Operations on-Airport can delay manned aircraft as well), and other circumstances can cause a denial out of the blue.
LAANC is fairly straight forward for airports who are currently IN the LAANC system. If you have an airport that is NOT currently in the LAANC system you need to go
FAADroneZone to the to request an airspace authorization. It's not hard but it's also not INSTANT.
@Thomas B has gotten these approved in his area for a couple of years.