vb.net get 数据问题

Public Shared Function GetData2(ByVal data As String) As String
Dim url As String = "http://api.jsform.com/api/v1/form/5a59a1b1bb7c7c374d50e6a5"
Dim request As HttpWebRequest = WebRequest.Create(url + "?" + data)
request.Method = "GET"
Dim code As String = Convert.ToBase64String(System.Text.Encoding.ASCII.GetBytes(String.Format("{0}:{1}", 13891751231, 123456)))
request.Headers.Add("Authorization", "Basic " + code)
Dim sr As StreamReader = New StreamReader(request.GetResponse().GetResponseStream)
Return sr.ReadToEnd
End Function
get数据，显示"message":"invalid hexadecimal representation of an ObjectId: [13891751231]","status":"error"}，求大师指导。
在开始使用之前，您需要在“账户”中获取API Key/Secret，只有通过这两个参数才能获取API的访问权限。
您每次进行API调用时，都需要将API Key&Secret放到HTTP请求的Header中。例如，使用curl来获得某个表单提交的数据，
API Key&Secret咋加啊？