Try this:
1. Group by employee.
2. Create a running total:
Field to Summarize: Date
Summary: Distinct Count
Evaluate on: Formula - {MyTable.Status} = "Working"
Reset on: Change of group - Group from step 1.
You'll create another one for status = "Leave".
When using running totals, the numbers have to be displayed in the group footer - they're not available for the group header. If you MUST have the numbers in the header, there's another way this can be done. Let me know and I'll post it.
-Dell