AWS transcoder Captions Embedded missing

Question

We have a problem with MP4 video containing 5 languages captions embedded. After transcoding in AWS transcoder, file contains no languages.

I want to keep original captions for languages and converting them into an other format (mov-text, cea-608 or cea-708)

The Job id : 1497397548070-s8ituv

Input Caption :

'InputCaptions': {
     'MergePolicy': 'MergeRetain',
     'CaptionSources' : []
}

Output Caption :

'Captions': {
     'CaptionFormats': [{
           'Format': 'cea-708'
     }]
}

1. Is it because the captions of my input file is not in good format mov-text, CEA-608 or CEA-708?
2. Is it the good maneer to create the job for keep original captions and convert them?
3. Is it because of my preset (proprity of Audio or Video) ?

Can you help us ? Best regard.