Weather you use VS or SPD to develop declarative SharePoint 2013 workflows for .net 4.0 make use you never use the local variable with the name "Result". It conflicts with the internal keywords of .xaml and causes the error that Activity with xyz guide not found at the deploy step.
it took me three hours to find this tiny bug that broke my big workflow.
Someone should report it to WF team so they fix it.
Shahid Roofi