Unable to assign multiple checkbox selected values to a CDT

I have a CDT "AT_employeelanguages"

like below-attached screen

I am pulling the below table data using an expression and referring to the same using an expression rule AT_GetLanguages()

When I use the below code, nothing is saved into my CDT "employeelanguages". Can someone guide me to solve this issue? Thanks in advance.

a!localVariables(
local!languages: rule!AT_GetLanguages(),
local!selectedLanguages,
a!formLayout(
label: "Test" & local!selectedLanguages,
contents: {
a!checkboxField(
label: "Languages Known",
choiceLabels: index(local!languages, "name", null),
choiceValues: index(local!languages, "languagenumber", null),
value: local!selectedLanguages,
saveInto: {
local!selectedLanguages,
a!save(
ri!employeelanguages,
local!selectedLanguages
)
}

)
}
)

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