The reference genome
mm10 is already installed at all of the usegalaxy.* servers, and is indexed for most tools.
Some tools require that the input to the tool has the datatype assigned. This can filter options on the tool form. In your case, this would be assigning the metadata for the datatype
mm10 to the input. Try doing that and see if it resolves the problem. How-to: Metadata
If you are running your own Galaxy server or using some private Galaxy server, genomes are not added or indexed for tools by default. The genome will usually show up in the list of “databases” on the Upload or Edit attribute forms, but those are just references. The actual data need to be added, and that can include genomes that are not already in the list of databases (when you add the data, it will be added to that list). These prior Q&A topics explain how-to, along with some troubleshooting help. You need to be the administrator of the server to do this. If you are not the administrator, ask them to do it and maybe point them to the help.
If that doesn’t help, please explain with more details:
- Where are you working? URL if a public Galaxy server, or describe if other
- What tool are you using? Capture the full name and version from the top of the tool form and paste that back in your reply.
Let’s start there