When I send 0x50 I get nothing back but the following:
ff 00 04 00   

And that message comes after a long period of time; it looks more like a keepalive message than anything else. Does anyone know why I not getting the 0x25 ping value that I'm supposed to be getting?

Anyways, here's what I send:
[code]
01 ff 50 00 00 00 00 36 38 58 49 50 58 45 53 cd ..P....68XIPXES.
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 55 53 41 00 55 6e 69 74 65 .......USA.Unite
64 20 53 74 61 74 65 73 00                      d States.
Length: 57
[/code]

And here's some code if it is easier on your eyes:
[code]
public class SidAuthInfoCS extends BNCSBuffer
{

public SidAuthInfoCS(String productID)
{  // 0x01 is added at front by BNCSBuffer to signify game protocol
super((byte) 0x50);       // message ID
        addDWord(0x00);     // protocol id
        addString("68XI");        // platform id
        addString(productID);      // product id
        addDWord(0xCD);     // version byte
        addDWord(0x00);       // product language - ok to set to 0
        addDWord(0x00);               // local ip - ok to set to 0
        addDWord(0x00);               // time zone bias
        addDWord(0x00);       // locale id
        addDWord(0x00);       // language id
        addNTString("USA");       // country abbrev.
        addNTString("United States"); // country
}
}
[/code]

Thanks in advance.

You're sending a length of zero for your first message.  I'm rather surprised the server didn't ban you outright for that.