Invalid character in a Base-64 string.. Help!!

I got this error message “Invalid character in a Base-64 string” and I don’t know what is causing it… do you have any idea about it?

Yes I do, but you can't expect me to guess what the real problem is, can you? :)

Show me the Base64 string, is it an image, and where are you getting the string from? Where did that source get the string from, and so on...

am trying to make a newsletter subscription page.. the user will enter his email and thien click the image button... it will first call a function to validate the user entries in the textbox.. then it should take the string to the server side code to check if the entered email exists or not in the database...if yes, give a message. if no, store it in the database...

the error is happening when i click on the image button... exactly after the client side validation (javascript function is running fine).

so any idea?