Parameter is not valid error occurred.

hello,

i am working on a web application where i have to create the image in Database
and have to retreive the image from database.

actually the Database is a third party system. now i have to pass the content of
photo as string and have to get that back as string.

now when i get the image back from db and want to create an image, i get
"Parameter is not valid" error.

 

Please help.