Abaqus subroutine error: "Sensor cannot be found but is accessed in VUAMP."

[gracem]

I am trying to run an abaqus job which has an initial step followed by a restart file which calls on a user subroutine to determine muscle forces based on displacement. When I call the subroutine in the initial step I get the error "***ERROR: Sensor KIN_AP_SENSOR cannot be found but is accessed in VUAMP. Please make sure that this sensor is defined for this step."
Yet I have the sensor defined in the .inp file as
*OUTPUT, HISTORY, SENSOR, TIME INTERVAL=1e-5, NAME=KIN_AP_SENSOR
*ELEMENT OUTPUT, ELSET=AXIS_R_TF_EXT_AP
CU1,
and my Fortran code is
tfAP = vGetSensorValue('KIN_AP_SENSOR',jSensorLookUpTable,
* sensorValues)
Any help on what the issue could be would be appreciated. Thanks!