Date Range as Parameter

Why so complicated?

Try this is the top of your query, assuming the name of your parameter is "String":

--DECLARE @string VARCHAR(20) = '7/22/2014-7/29/2014'

DECLARE @startDate DATE, @endDate DATE

SET @startDate = LEFT(@string,CHARINDEX('-',@string)-1)
SET @endDate = RIGHT(@string,LEN(@string)-CHARINDEX('-',@string))

--SELECT @startDate, @endDate

select * from mytable where theDate between @startDate and @endDate