Workflow-execute the Business Workplace workitems from explorer

Hi,

I have made a custome workflow with screens ,custom business object etc.Its working fine in R3.I am able to execute all my workitems through SAP business workplace.

Problem im facing is to execute them from ESS(Employee self service -login i.e ITS login).I created internet services fo all the transactions used in the workflow and published them also.i can see the workitem in ESS inbox but gives error when i click on execute workitem.Urgsent help is required.