1. You have used the "=" operator so it will only filter on exact match, you could create a list of Employees, either as a dataset or by typing it in to "Available Values" and use that to populate your list, meaning that you should always get data.

2. From your third ss you have no dates populated, make sure that the data type for the @StartDate and @EndDate are in fact dates. You can also put in default values.

For example, if you want to run the report for the last 7 days you would put the following in for @StartDate default value:

=DATEADD("D", -7, TODAY())

and the following in for @EndDate

=TODAY()