All I can say, that Guatemala was on the April 2 OECD report as a grey listed country along with Austria, Switzerland, and others. These are removed, but I have never heard, that Guatemala has been signed 12 OECD standard double taxation agreements, so probably your country is still on the list.
Here you can check the report above mentioned:
http://www.oecd.org/dataoecd/38/14/42497950.pdf
Here is the current situation (latest):
http://www.oecd.org/dataoecd/50/0/43606256.pdf