key is not unlocking cylindrical lock

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The Von Duprin 7500 mortise lock body ships in the NL mode.  Either the function of 7500 lock body has not been changed to the Classroom function or the NL Drive screw is not all the way down. Step...
  Tips for changing the function: The NL Drive screw will not be visible when lock body is set to Classroom function There is locktite on the screw that makes it seem like its turned down enou...
The 98/99 rim and vertical rod exit devices are shipped with NL drive screw to function as a Night Latch. To convert the device to Class Room, remove the NL Drive Screw on 98/99 center case ass...
T381 Classroom Security Lock is not a "true" classroom security / Intruder lock function. The T381 is classified as a ANSI/BHMA F88 function: Defined as Grade 1, Apartment, Exit or Public Toil...
The keycam may have failed, example here, the latest design keycam can be easily identified as the colored changed to black. Replace either the keycam or chassis as needed to r...
 This could also happen if the tailpiece isn't installed in a KIL, FSIC, or SFIC cylinder.  The FSIC driver also could have come loose from the core in the spindle.
The 7500 mortise lock should be configured for NL function as shipped not as Classroom. See figure 4-3 in E996L instructions.
Installers have reported that their AD-CO Series cylindrical or mortise locks will unlock whenever the outside lever is lifted.    This will occur if the outside spindle (square post) is install...
With the new FW package 2.19.0; AD300 FW 2.17.0 and AD400 FW 2.17.0 (released 09/23/2011) the firmware looks for a motor clutch switch change after a motor move command. If there is no motor clutch...
If the triangles in the spring cage spindle are not aligned properly the motor will not move enough to change the clutch switch. Is is very likely with a lock on the bench; but a properly install...
When the new firmware moves the motor three times without seeing the clutch switch change it reports to the SUS diagnostics that the motor is stalled. Aligning the triangles will let the motor move...
If the lock is mounted on the door, it is necessary to adjust the mortis/cylinder tightness and spring cage tailpiece alignments, making sure there is no binding or stopping of the spring...
Just align the triangles per the installation instructions to allow full motor movement.   - This will eliminate the SUS motor STALL report. - This will eliminate the three ...
After rotating  the key to unlock the lock, you must return the key to its normal position to remove it. 
Indicator not extended Indicator extended
The indicator on a cylindrical hotel lock is a small pin that projects outward from the face of the cylinder plug (Figure 1) when the inside push button is depressed.  When this pin is pr...
Falcon D series deadbolts will not accept Schlage Key-in-lever cylinders. The faceplate plug hole is smaller in diameter than the Schlage plug and does not fit flush when i...
For a Schlage "C"  keyway:  Specify "CP6" as the cylinder suffix when ordering  D100 or D200 locks (All other Schlage keyways are not available).
When you want to periodically disable and block access to a certain room in a building or an entrance door, that’s when you would need to use a Lockout Cylinder. See full document.