RSA Encryption Bad Data Error

I have an application that is to take user inputed values (such as credit card numbers) and encrypt them, then write the data to a SQL table, and eventually retrieve the data from SQL and decrypt the data.
I am receiving a "Bad Data" error when I retrieve and try to decrypt the record from SQL, BUT... if I decrypt the data before writting it to SQL (straight from the textboxes) it decrypts fine.

I am converting the textbox strings using (FromBase64) as it has been said that (UTF-8 Encoding) can cause this error.

In the table the data type that I am using is varbinary for the encrypted data.

I'm using XML files to store the Public and Private Keys

If this makes any sense does anybody have any insight?

It's Okay I got it,

Must Use Binary not VarBinary, and of course the most important, set the data length to 128