This happens when you have had a change in your employment status (transfer, extension, rehire, etc).  You can fix this problem by following these instructions:

• Change the 'View By' option to 'Week' (it currently reads 'Calendar Period')
• On the "Date" drop down menu, select the first day you are required to enter hours for.
• Then select the green arrow ‘refresh’ button to bring up the required period.
• From here you can enter your hours and time reporting code as usual.

Note:   You are required to select the 'Submit' button after each weekly entry for the period that is grayed out.