Hi,
As far as I remember, you cannot make mapping between activity entities and the "other" entities which are mapped using the "Regarding" field. I personally see this as something similar to a bug or lack of expected function but that just seems to be how
CRM works. You can create a workaround by making javascripts that exectute onload on the "Sample Request" and use the REST API to get the data from CRM that you need from the contact.
Gustaf Westerlund, MVP, CEO and Chief Architect at
CRM-Konsulterna in Sweden
Blog: http://gustafwesterlund.blogspot.com
Swedish Dyn CRM Forum: http://www.crmforum.se