Request.BinaryRead(Request.TotalBytes) throws error for large files

I have code that accepts binary data via POST and reads in an array of bytes. For files larger than 200 Kb, the operation fails. I've checked with my sysadmin (we're running IIS 7) to see if there was a limit in our configuration and he says there is none, and suspects it is a problem with the code. Does anybody here see any potential problems? Here is my code:

Public Sub Initialize
  If Request.TotalBytes > 0 Then
    Dim binData
      binData = Request.BinaryRead(Request.TotalBytes) ' This line fails'
      getData binData
  End If
End Sub


 Private Sub getData(rawData)
    Dim separator 
      separator = MidB(rawData, 1, InstrB(1, rawData, ChrB(13)) - 1)

    Dim lenSeparator
      lenSeparator = LenB(separator)

    Dim currentPos
      currentPos = 1
    Dim inStrByte
      inStrByte = 1
    Dim value, mValue
    Dim tempValue
      tempValue = ""

    While inStrByte > 0
      inStrByte = InStrB(currentPos, rawData, separator)
      mValue = inStrByte - currentPos

      If mValue > 1 Then
        value = MidB(rawData, currentPos, mValue)

        Dim begPos, endPos, midValue, nValue
        Dim intDict
          Set intDict = Server.CreateObject("Scripting.Dictionary")

          begPos = 1 + InStrB(1, value, ChrB(34))
          endPos = InStrB(begPos + 1, value, ChrB(34))
          nValue = endPos

        Dim nameN
          nameN = MidB(value, begPos, endPos - begPos)

        Dim nameValue, isValid
          isValid = True

          If InStrB(1, value, stringToByte("Content-Type")) > 1 Then

            begPos = 1 + InStrB(endPos + 1, value, ChrB(34))
            endPos = InStrB(begPos + 1, value, ChrB(34))

            If endPos = 0 Then
              endPos = begPos + 1
              isValid = False
            End If

            midValue = MidB(value, begPos, endPos - begPos)
              intDict.Add "FileName", trim(byteToString(midValue))

          begPos = 14 + InStrB(endPos + 1, value, stringToByte("Content-Type