Check the date format being returned by Date.Now() is in the same format required by the DB, had a similar problem myself and used the Format() function to correct the format first.
Replace the actual format you need in the format function below this is the one I had to use for a MySQL db.
command.CommandText = "UPDATE Electric_Cables SET Actual_Finish= '" + Format(Date.Now(), "yyyy-MM-dd") + "' WHERE Asset_ID=" + TextBox1.Text
The alternative is to use OLEDB .Parameters which will construct and convert parameters content correctly.
command.CommandText= "UPDATE Electric_Cables SET Actual_Finish=? WHERE Asset_ID=" + TextBox1.Text
command.prepare
command.Parameters.Add(Date.Now)
Good Luck.