Chain sub rule throwing error in feature editor

Trying the feature code from this example of the official fea spec:

lookup REMOVE_CAKRA {
    sub ka ka.pas_cakra.ns by ka;
} REMOVE_CAKRA;

lookup REORDER_CAKRA {
    sub ka by ka.pas_cakra ka;
} REORDER_CAKRA;

lookup REORDER_CHAIN {
    sub ka' lookup REMOVE_CAKRA lookup REORDER_CAKRA ka.pas_cakra.ns' ;
} REORDER_CHAIN;

will fail with an “Expected glyph or glyph class” in the third lookup.