Asp.Net将图像添加到SQL表中......我做错了什么？

I have done this previously but in a different way. I am trying to get the code below to work. If I do not cast 'OriginalPhoto' or 'Thumbnail' an error occurs. Implicit conversion from data type varchar to varbinary(max) is not allowed. Use the CONVERT function to run this query. I don't understand why it asking to cast. However if I do cast it, the images add to the database just fine in a binary data format. When trying to view the images, i get the error 'Unable to display the given data'. I have inserted both byte[] into a table using a SqlDataAdapter and that works. I want to use this method though, what am I doing wrong? I have done this previously but in a different