Activation failed: Missing external jar

Hi,

I'm using an external jar in my WebDynpro development for ESS. I placed this jar file in the lib folder. Everything works fine when deploying to the development server directly.

During activation, i got the error which describing the imported classes from the jar file cannot be found. I'm confirmed this jar file was uploaded into the open activity prior to the activation.

How to solve this problem?

Any help would be highly appreciated. Thanks.

- julius