Python in AzureML fail to pass dataframe without changes

when trying to pass data without doing anything in python, getting this error:

Error 0085: The following error occurred during script evaluation, please view the output log for more information:
---------- Start of error message from Python interpreter ----------
Caught exception while executing function: Traceback (most recent call last):
  File "C:\server\invokepy.py", line 175, in batch
    rutils.RUtils.DataFrameToRFile(outlist[i], outfiles[i])
  File "C:\server\RReader\rutils.py", line 28, in DataFrameToRFile
    rwriter.write_attribute_list(attributes)
  File "C:\server\RReader\rwriter.py", line 59, in write_attribute_list
    self.write_object(value);
  File "C:\server\RReader\rwriter.py", line 121, in write_object
    write_function(flags, value.values())
  File "C:\server\RReader\rwriter.py", line 104, in write_objects
    self.write_object(value)
  File "C:\server\RReader\rwriter.py", line 121, in write_object
    write_function(flags, value.values())
  File "C:\server\RReader\rwriter.py", line 71, in write_integers
    self.write_integer(value)
  File "C:\server\RReader\rwriter.py", line 147, in write_integer
    self.writer.WriteInt32(value)
  File "C:\server\RReader\BinaryIO\binarywriter.py", line 26, in WriteInt32
    self.WriteData(self.Int32Format, data)
  File "C:\server\RReader\BinaryIO\binarywriter.py", line 14, in WriteData
    self.stream.write(pack(format, data))
error: cannot convert argument to integer

---------- End of error message from Python  interpreter  ----------
Start time: UTC 05/26/2016 13:16:01
End time: UTC 05/26/2016 13:16:13

here is the data i'm trying to pass:

here is the experiment:

and the python code:

after talking to Microsoft support, the problem was that the "Execute Python Script" module cannot return empty values. this can be solved by adding a "Clean Missing Data" module before reading it from python: