Install Problems

I made it all the way through till the last step:

Fill in the form as follows:
Title: vBChat Auto Prune
Day of the Week: *
Day of the Month: *
Hour: 0
Minute: 2
Log Entries: Yes
Filename: ./includes/cron/vbchat.php

Now submit the form.

When i hit the submit button i get the following error:

Invalid Filename Specified