failed to invoke FormDataIntegration.importData

Am getting the following error message when i try to import data using "FormDataIntegration" client.

Please advise!

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!MESSAGE failed to invoke FormDataIntegration.importData
!STACK 0
ALC-DSC-003-000: com.adobe.idp.dsc.DSCInvocationException: Invocation error.
at com.adobe.idp.dsc.component.impl.DefaultPOJOInvokerImpl.invoke(Defaul tPOJOInvokerImpl.java:210)
at com.adobe.idp.dsc.interceptor.impl.InvocationInterceptor.intercept(In vocationInterceptor.java:134)
at com.adobe.idp.dsc.interceptor.impl.RequestInterceptorChainImpl.procee d(RequestInterceptorChainImpl.java:44)
at com.adobe.idp.dsc.transaction.interceptor.TransactionInterceptor$1.do InTransaction(TransactionInterceptor.java:74)
at com.adobe.idp.dsc.transaction.impl.ejb.adapter.EjbTransactionBMTAdapt erBean.doRequiresNew(EjbTransactionBMTAdapterBean.java:218)
at com.adobe.idp.dsc.transaction.impl.ejb.adapter.EJSLocalStatelessEjbTr ansactionBMTAdapter_3af08fdf.doRequiresNew(Unknown Source)
at com.adobe.idp.dsc.transaction.impl.ejb.EjbTransactionProvider.execute (EjbTransactionProvider.java:133)
at com.adobe.idp.dsc.transaction.interceptor.TransactionInterceptor.inte rcept(TransactionInterceptor.java:72)

...................

Caused by: java.lang.NoClassDefFoundError: com/adobe/formServer/utils/StringUtils
at com.adobe.livecycle.formdataintegration.server.FormData.importData(Fo rmData.java:51)
at sun.reflect.GeneratedMethodAccessor644.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.adobe.idp.dsc.component.impl.DefaultPOJOInvokerImpl.invoke(Defaul tPOJOInvokerImpl.java:181)
... 57 more

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