Make sure that the format of the filenames in your log directory match the format that we're trying to use.
I just looked at mine, and noted that in my case the code would have to read
write -dw $+ *split $+($logdir,$network,\,$chan,.,$date(yyyy),$date(mm),$date(dd),.log)
If you're going to use an * in your search (as a wildcard), then you have to use the w to show that it's a wildcard search, rather than the s
