SQL server ERROR

Question

AM getting this error while performing this query operation

Msg 241, Level 16, State 1, Line 1

Conversion failed when converting date and/or time from character string.

here' s my query

SELECT 

 MaxDate,

 MinDate,

DATEDIFF(D, MaxDate, MinDate)

FROM (

SELECT

     (SELECT MAX(TDate) ) AS MaxDate

    ,(SELECT MIN(TDate) ) AS MinDate

FROM EDATA

)a