why String is not convertible to datetime? : I am passing 2 dates to store procedure but conversion throws error 'String not convertible to datetime'

     txtFromDate.Text = DateTime.Now.ToString("dd/MM/yyyy");
     txtToDate.Text = DateTime.Now.ToString("dd/MM/yyyy");

     System.Data.DataTable dt = RejFiles.RejectedFiles(Convert.ToDateTime(txtFromDate.Text.Trim()), Convert.ToDateTime(txtToDate.Text.Trim()), user.OfficeID, user.Type_ID);


SP:

    ALTER PROCEDURE [dbo].[usp_RejectedFiles] 
    (  
     @FromDate SMALLDATETIME,  
     @ToDate SMALLDATETIME,  
     @OfficeID INT=0,  
     @Type INT=0
    )  

and db stores the dates in particular table like this:

    2014-03-01 00:00:00

