Error while calling StartProcessWithContext method

Can you please help with the following error that we are getting when we try to refer the Advantys.Workflow.Web.Services.Processes.Runtime.dll from our RESTful WEB API.
We tried hosting the web API under both IIS webapp \wfgen or \wfgen\ws folders , but getting the below error.

We are trying to create the process instance using Web API.

An error has occurred during the process workflow: ProcessCreateInstance: The file ‘e:\wfgen\webapi\App_Data\Files\Dataset\design\2017\04\17\127896-1.html’ is not found.
System.Exception: An error has occurred during the process workflow: ProcessCreateInstance: The file ‘e:\wfgen\webapi\App_Data\Files\Dataset\design\2017\04\17\127896-1.html’ is not found.
at Advantys.Workflow.Engine.WorkflowsManager.ProcessCreateInstanceWithContextDataSet(Int32 processId, String processName, Int32 processVersion, Boolean test, DataSet contextDataSet, WorkflowUserIdentity requesterIdentity, WorkflowUserIdentity realUser)
at Advantys.Workflow.Web.Services.Processes.Runtime.RuntimeService.StartProcessWithContext(String workflowContext).