error in adding specific sequences when building kraken2-custom database

[alarasutcu]

Hi,

I am trying to build a custom database. I am having some issues with being able to add my sequences to the database.

I am using specified line to add ~38k viral sequences to the database,
kraken2-build --add-to-library <path_to_sequences.fna> --db <kraken_path> but I am not certain that they are being added.

When it comes time to building the database kraken2-build --build --db <kraken_path> it is saying that 0 sequences were processed.

And when I inspect the output this is what I see:

Do you have any suggestions of what to do? Also, it would be helpful to understand the limitations of what can be added to the database?