(setq my-capture-template-next "* NEXT %?\n:PROPERTIES:\n:CREATED: %U\n:END:\n\n")
(setq org-capture-templates
`( ; Note the backquote here!!
("1" "first version with string" entry (file+headline "~/share/all/org-mode/
misc.org" "shorts")
"* NEXT %?\n:PROPERTIES:\n:CREATED: %U\n:END:\n\n" :empty-lines 1)
("2" "second version with variable" entry (file+headline "~/share/all/org-mode/
misc.org" "shorts")
,my-capture-template-next :empty-lines 1) ; and comma before my-capture-..
))
My guess is you need to evaluate my-capture-template-next before putting it in org-capture-templates and the backquote/comma above do that.