'File cannot be executed' error in compiled function

I've got a compiled function 'process_unpacked_can_messages.m' that calls a sub-function 'steady_state_analysis.m'. It runs daily, and so far it's been running fine. But I got an error yesterday:

The file "C:\Users\matlab\AppData\Local\Temp\matlab\mcrCache9.2\combin0\sub_functions\Steady State Analysis functions\steady_state_analysis.m" cannot be executed. line 64 in process_unpacked_can_messages

The function was compiled using MATLAB Compiler Version 6.4 and is run using MATLAB Runtime 9.2.