Based on the code you provided, it seems like you are trying to use the 'angvellog' function to log angular velocity, the following things could be causing the issue:
Device Compatability: Ensure that the mobile device you are using supports the logging of angular velocity data.
Sensor configuration: Make sure sensor configuration is enabled, you can do this by 'Sensors > More > Sensor Access' in MATLAB mobile.
For further information about the angvellog function checkout its documentation angvellog
