Exception in thread "main" com.box.sdk.BoxAPIResponseException: The API returned an error code [400]

I am getting an exception in BoxFolderTreeBuilder as well as in all sample programs when i run these in eclipse...

at code statement

api = new BoxDeveloperEditionAPIConnection(USER_ID, DeveloperEditionEntityType.USER, boxConfig,
accessTokenCache);

BoxDeveloperEditionAPIConnection serviceAccountClient = BoxDeveloperEditionAPIConnection
.getAppEnterpriseConnection(boxConfig);

Exception in thread "main" com.box.sdk.BoxAPIResponseException: The API returned an error code [400]

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Exception in thread "main" com.box.sdk.BoxAPIResponseException: The API returned an error code [400]
at com.box.sdk.BoxAPIResponse.(BoxAPIResponse.java:92)
at com.box.sdk.BoxJSONResponse.(BoxJSONResponse.java:32)
at com.box.sdk.BoxAPIRequest.trySend(BoxAPIRequest.java:579)
at com.box.sdk.BoxAPIRequest.send(BoxAPIRequest.java:354)
at com.box.sdk.BoxAPIRequest.send(BoxAPIRequest.java:329)
at com.box.sdk.BoxDeveloperEditionAPIConnection.authenticate(BoxDeveloperEditionAPIConnection.java:358)
at com.box.sdk.BoxDeveloperEditionAPIConnection.getAppEnterpriseConnection(BoxDeveloperEditionAPIConnection.java:179)
at com.box.sdk.BoxDeveloperEditionAPIConnection.getAppEnterpriseConnection(BoxDeveloperEditionAPIConnection.java:211)
at box.caseroads.BoxFolderTreeBuilder.main(BoxFolderTreeBuilder.java:256)