Error with uploading file using Sharpbox

Question

I am trying to upload a file to sharpbox.

my app is registered as an app that can access to any of the files in my Dropbox account. It creates folders with no problem. But when It's trying to upload a file, I get the following exception:

Exception of type 'AppLimit.CloudComputing.SharpBox.Exceptions.SharpBoxException' was thrown.

I use the following code:

    Dim accessToken As ICloudStorageAccessToken
    Dim dropBoxStorage As New CloudStorage()

    If IO.Directory.Exists(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud") Then
        Using fs = File.Open(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud/SharpDropBox.token", FileMode.Open, FileAccess.Read, FileShare.None)
            accessToken = dropBoxStorage.DeserializeSecurityToken(fs)
        End Using
        Using reader As New ResourceReader(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud/SN.bsn")
            For Each i As DictionaryEntry In reader
                unpass.Items.Add(i.Value)
            Next
        End Using
    Else
        IO.Directory.CreateDirectory(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud")
        IO.File.WriteAllBytes(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud/SharpDropBox.token", My.Resources.SharpDropBox)
        Using writer As New ResourceWriter(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud/SN.bsn")
            writer.AddResource("1", mystring)
            writer.AddResource("2", mystring1)
            writer.Close()
        End Using
        Using reader As New ResourceReader(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud/SN.bsn")
            For Each i As DictionaryEntry In reader
                unpass.Items.Add(i.Value)
            Next
        End Using


        Using fs = File.Open(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud/SharpDropBox.token", FileMode.Open, FileAccess.Read, FileShare.None)
            accessToken = dropBoxStorage.DeserializeSecurityToken(fs)
        End Using

        firsttime = True
    End If


    Dim dropBixConfig = CloudStorage.GetCloudConfigurationEasy(nSupportedCloudConfigurations.DropBox)
    Dim storageToken = dropBoxStorage.Open(dropBixConfig, accessToken)

    If firsttime = True Then
        Try
            dropBoxStorage.GetFolder("/My App Files/" + mystring)
            IO.Directory.Delete(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/cloud")
            Call Me.errornew()
        Catch ex As Exception
            Dim remoteDirName As String = "/My App Files/" + mystring1
            Dim targetDir As String = My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData
            Try
                dropBoxStorage.CreateFolder(remoteDirName)
                dropBoxStorage.CreateFolder(remoteDirName + "sysdata")
                dropBoxStorage.Open(dropBoxConfig, accessToken)
                IO.File.WriteAllText(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/sysdata.brsi", pass)
                dropBoxStorage.GetFolder("/My App Files/" + mystring1 + "sysdata")
                dropBoxStorage.UploadFile(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/myfile.txt", "/My App Files/" + mystring + "sysdata")
                IO.File.Delete(My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData + "/sysdata.brsi")
             call dosomethingafterwards()
            Catch ex1 As Exception
                MsgBox("An error was occured while My App tried to download your files, and it will now switch to offline mode. Try to connect the internet, and then restart My App. We're sorry.")
                Call new1()
            End Try
        End Try
        dropBoxStorage.Close()

    Else
        Dim remoteDirName As String = "/My App Files/" + mystring
        Dim targetDir As String = My.Computer.FileSystem.SpecialDirectories.CurrentUserApplicationData
        Try
            Dim remoteDir = dropBoxStorage.GetFolder(remoteDirName)
            DownloadFolder(dropBoxStorage, remoteDir, targetDir, remoteDirName)
        Catch ex123 As Exception

            MsgBox("An error was occured while My App tried to download your files, and it will now switch to offline mode. Try to connect the internet, and then restart My App. We're sorry.")
            Call dosomethingafterwards()

        End Try


        dropBoxStorage.Close()
    End If

What is wrong in my code, and how can I fix it?