Butt weld to threaded fittings

Hello guys.

'Opened my assembly and noticed that one of my 90 degree threaded elbow fittings turned into a butt-weld one.

Been trying to replace it for the past hour and working on it but no luck to this time.  I must be missing on something.

Your usual assistance I shall appreciate.  Using 2014.

Thank you all.  =D

SolidworksRouting