As Rohan Leuva said - use parameterized queries. Not just to be safe from SQL injection, but because they give easy solutions to problems like this.
For example:
SqlDataAdapter ErrorListTableAdapter = new SqlDataAdapter();
ErrorListTableAdapter.SelectCommand =
new SqlCommand( "SELECT * FROM ErrorList WHERE (Date BETWEEN @Date1 AND @Date2)",
conn);
ErrorListTableAdapter.SelectCommand.Parameters.Add("@Date1", SqlDbType.Date).Value
= FromDateTimePicker.Value.Date;
ErrorListTableAdapter.SelectCommand.Parameters.Add("@Date2", SqlDbType.Date).Value
= ToDateTimePicker.Value.Date;