An error sometimes made is the confusion of discussion regarding Greece’s Eurozone entry with the controversy regarding usage of derivatives’ deals with U.S. Banks by Greece and other Eurozone countries to artificially reduce their reported budget deficits. A currency swap arranged with Goldman Sachs allowed Greece to "hide" 2.8 billion Euros of debt, however, this affected deficit values after 2001 (when Greece had already been admitted into the Eurozone) and is not related to Greece’s Eurozone entry.

What error is sometimes made by tying Greece's Eurozone entry with?