What can cause ERASE to generates a file not found error?

I have a function which erases temporary files in a specific directory and for some kind of reason, this morning my error log indicates that it had an error at that line.

My line is really simple:

ERASE tcDir+ALLTRIM(laFile[lnCompteur,1])

I tried manually the ERASE command by indicating non existent files or non existing directories and I was unable to generate an error.