Selenium WebDriver Grid 2: screenshot is taken at wrong time or from wrong node
===

I run my tests under Selenium Grid 2 which has a Hub and 3 nodes on different PCs. In case of failures my tests invoke taking screen shot and publish logs into TestNG report with attached screen shot:<br><br>
<i>
WebDriver augmentedDriver = new Augmenter().augment(driver);<br>
File scrFile = ((TakesScreenshot) augmentedDriver).getScreenshotAs(OutputType.FILE); <br>
...<br>
org.testng.Assert.fail("TEST OUTPUT:" + logBuffer.toString() + " " + screenShotMsg + "STACKTRACE:");<br><br>
</i>

As a result I can see that sometimes the screenshot doesn't correspond to the logs. 
E.g. the screen shot shows the "Welcome" page and logs shows that the error occurred on "Patient List" page.

I have an assumption that screenshot is taken at wrong time or from wrong node.

How can I find the reason of this behavior and fix that?