The return types for the following stored procedures could not be detected

This problem occurs whenever the designer cannot figure out the return type of the SP.
Same problem and solutions described here
How to get multiple result set of procedure using LINQ to SQL

Basically this is the solution from the link:

Avoid using #temp Table in your stored procedure, instead of you can use Table type variable like below (@TempTable)

Ex:

DECLARE @TempTable TABLE
(
  AttributeID INT,
  Value NVARCHAR(200)
)

INSERT INTO @TempTable Select * from Attribute

OR

--Execute SP and insert results into @TempTable
INSERT INTO @TempTable Exec GetAttribute @Id

You can do all operation which you was doing with #Temp table like
Join, Insert, Select etc.