Mr. PA3040 is right !
You should check the frequency at its legs so that i can show exactly what freq its producing.
If you check at some other parts, based on your program written the clocks gets distributed and you might assume that the crystal might not be working properly.
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If you measure it as 50 hz instead of 20Mhz before you solder it, then its doesnt work properly. before or after soldering also the way you check is probing at its legs only !