java.lang.NoClassDefFoundError: com/sap/mw/jco/JCo

Hi:

I am using NWDS SP16. I have created proxy class for a rfc using SAP Enterprise Connector.

I have created a j2ee web dc and added the com.sap.mw.jco dc in the used dc's list.

Then I tried to create a Jco connection, I got the error java.lang.NoClassDefFoundError: com/sap/mw/jco/Jco

Any help please.