Update a CDT from multiple sources

 I have a CDT of several fields. The majority of fields get populated via a rule. However I also need to update one of the fields with a value from a text input. To do this I have the following :

a!textfield(
value:ri!test
saveInto:{

     ri!test,
     a!save(target:ri!myCDT,
                value:rule!getData),
    a!save(target:ri!myCDT.FIELD4,
               value:"DATA1)
)

However when I enter text in this field, and tab off (thus executing the save) I'm getting an error

Definition: Expression evaluation error in rule 'TEST' : An error occurred while executing a save: java.lang.IllegalArgumentException: Invalid index: Cannot index property 'fIELD4' into type List of Number (Integer)