Solution: Problem is most likely that RPC is not configured for your linked server. That is not a default option, after all. You can see what settings are configured with exec sp_helpserver, run on the client server (not the linked server).
If 'rpc,rpc out' is not in your results, then the the linked server isn't configured for RPC. To do so, run these two commands on the client server:
exec sp_serveroption @server='myLinkedServer', @optname='rpc', @optvalue='true'
exec sp_serveroption @server='myLinkedServer', @optname='rpc out', @optvalue='true'