If the first batch in your sproc doesn’t return a result set then it will not be in the dm view that radzen uses to infer the schema. The solution is to make sure the first statement in your sproc is a select statement. The workaround is to add a dummy select statement to your sproc like
select * from dbo.Dummy
As explained here
You also need to be on sql server 2012 and if you want to use the results in radzen then make your dummy results resemble the actual sproc resultset.