MS SQL Server Report Builder_Concatenate data type "date" and "time"

I am working on MS SQL Server Report Builder 2008 r.

I have a Dataset contains DateEntry (date,null) and TimeStampAuto (time(7),null). I am trying to write an expression for concatenating those two values, so I can put it under DATETIME column on the report table. I tried the following but it does not work. It displays "#Error."

=First(Fields!DateEntry.Value, "Report1) & " " & First(Fields!TimeStampAuto.Value, "Report1)

When I just put the first part of the expression shown above, the report displays the date with some random time value (5/1/2015 12:00:00 AM). However, I did not put any time value on DateEntry. I only put the dates. When I put the second part of the expression shown above, the report displays correct time that the data has.

I don't know why I can not concatenate those two.