function GetDataSetLabelFromValue(ByVal id as integer) as String
	dim i as integer
	i = 0
		for i = 1 to Report.Parameters!multivalueid.Count()
			if Report.Parameters!multivalueid.value(i) = id  then
 				GetDataSetLabelFromValue = Report.Parameters!multivalueid.Value(i)
		Exit For
		End if
	next i
End Function		

Hi Helixpoint, 

According to your report code, you want to get the multiple-parameter value based on id, right? 

In Reporting Services, if you want to get the one of the multiple parameter values, we can use Parameters!id.value(number) to get the required value. In your scenario, if you want to get the value based on the id, please refer to the below code: 

function GetDataSetLabelFromValue(ByVal id as integer) as String
	dim i as integer
		for i = 0 to Report.Parameters!multivalueid.Count()
			if i = id  then
 				GetDataSetLabelFromValue = Report.Parameters!multivalueid.Value(i)
		Exit For
		End if
	next i
End Function

If you have any other question, please feel free to ask. 

Regards,
Shrek Li