VB.Net Business API web service trouble

I am just getting started working on some tools to synchronize accounts with dropbox via the Business API, but I am having some trouble getting it working correctly. I am just simply trying to verify the web services at this point. I know that I am on the right track because it works as expected with SoapUI, but passing the data this way doesn't work. I suspect that my problem is that it isn't properly passing the Json blank line, {}, but why not? Any tips? For what it is worth, it is shooting back a 400 bad request. I can reproduce this same problem by not including the {} in SoapUI. I tested using ChilkatDotNet libraries with the postjson2 method and it works as expected, but I would rather not purchase the library for something that should just work.

    Dim postdata As String = "{}"
    Dim conn As New Net.WebClient
    conn.Headers("Content-Type") = "application/json"
    conn.Headers("authorization") = "bearer <validnumberhere>"
    Dim responseText As String = conn.UploadString("https://api.dropbox.com/1/team/get_info", postdata)