Java Connector dynamic link library librfc version is not up to date

Hi, I am a new Java Connector user. I wrote a simple TutorialConnect1 java class to test my SAP system connection. But I got the following error:

ava.lang.ExceptionInInitializerError: JCO.classInitialize(): Could not load middleware layer 'com.sap.mw.jco.rfc.MiddlewareRFC'

JCO.nativeInit(): Could not initialize dynamic link library librfc. Found version "620.0.949" but required at least version "620.0.1374".

at com.sap.mw.jco.JCO.<clinit>(JCO.java:735)

at TutorialConnect1.<init>(TutorialConnect1.java:29)

at TutorialConnect1.main(TutorialConnect1.java:61)

Exception in thread "main"

How do I update the version of my librfc?

Thanks for the help.

Chai