如何使用HttpWebRequest来调用接受字节[]参数的Web服务操作?

I am trying to call a [webmethod] from C#. I can call simple webmethod that take in 'string' parameters. But I have a webmethod that takes in a 'byte[]' parameter. I am running into '500 internal server error' when I try to call it. Here is some example of what I am doing.I am trying to call a [webmethod] from C#. I ca