Convert nvarchar to date and Get data between two date

I'm collecting data between two dates 01/12/2014 and 31/12/2014 but my data type is nvarchar.

Is my query right?

SELECT * 
FROM customer 
WHERE date >= CONVERT(datetime, '01/12/2014', 105) 
  AND date <= CONVERT(datetime, '31/12/2014', 105)

Result

Msg 242, Level 16, State 3, Line 1
The conversion of a nvarchar data type to a datetime data type resulted in an out-of-range value.

Can anyone solve this problem?