Trac cron plugin not working correctly for cron expression with day of week argument

[anonymous]

I want to run a cron every working day at 17:45hs, It seems is not parsing correctly the "?" for day of month?

This is the expression I use: * 45 17 ? * 1-5 *

And this is the log I get:

2012-06-06 11:16:17,113 Trac[scheduler] DEBUG: parsing cron expression * 45 17 ? * 1-5 *
2012-06-06 11:16:17,114 Trac[scheduler] ERROR: invalid cron expression: ? day already have a value