Help with DateTime

I just migrate my databse from sql 2000 to sql 2008 and the web site from iis6 (windows 2003) to iis7.5(windows 2008 R2)

When i try to view my web site i got this error: GET / |37|80040e07|The_conversion_of_a_varchar_data_type_to_a_datetime_data_type_resulted_in_an_out-of-range_value.
So i searched the web and found solutin using DateTime.Now.ToString. But i can't get it to work,

Here is the way i use it :  SQL = "INSERT INTO dbo.VisitesTest (dhVISDate) VALUES ( DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")  ) but this time i got this error : Object_required:_'DateTime'
What am i missing ?