Administrative processing - child visa under B2

[cluster]

Hi

I recently got my B2 visa renewed without interview, and subsequently my wife did her interview and got her visa issued. After that we applied for my daughter's visa through drop box as she is only 6 years old. We submitted both our visa copies as stipulated
However, its been more than 10 days now and the status shows as 'your visa is under necessary administrative processing...'
Why should it take so long. What kind of additional processing a child visa requires?
Can anyone share if they have had similar experience

Thanks

[Shameka]

Hi did they ever ask you why your daughter is not travelling with you?