Irregular behaviour of ipfs.object.patch.addLink api of js-ipfs

Question

I am trying to link a hosted IPFS object to a directory using the ipfs.object.patch.addLink command but it is showing irregular behaviour.

I have added a directory named abcd2 onto IPFS. This directory contains a file named file.html. While adding I am wrapping it under a directory, so the new structure is

""     <- root directory
|
---- abcd2
     |
     ---- file.html

I have added another file to ipfs named a.txt. I want to link a.txt to the root folder of the directory.

So the structure than should become ,

""
|
---- a.txt
---- abcd2
     |
     ---- file.html

To achieve this, I am running the command,

const cidnew = await ipfs.object.patch.addLink(<CID of root directory>, {
        Name: <name to keep of the file to link>,
        Tsize: <size of the file>,
        Hash: <hash of the file>
})

When I keep the name of the file as "a.txt" or "ab.txt" or "abc.txt" or "abcd.txt" is throws the following error,

HTTPError: Failed to add link to object: Invalid DAG-PB form (links must be sorted by Name bytes)

When I use any other name for the same file it works fine. I am using jsipfs for my implementation.

Does anyone know the reason and solution for this?