Problem with System call C_DIR_READ_START

Hello to all,

I've been tasked with debugging some code that uses calls to C_DIR_READ_START, NEXT and finish system calls to get a list of files in a specific app server path. The problem is this part of the program is only working randomly. Sometimes I run it and it gets the file list, sometimes i run it and it doesnt.

Does somebody know what can cause this random behavior?

Thanks in advance.