why raise configuration error?

[zillionare]

my mkdocs.yml:

site_name: Omicron

nav: 
  - Home: index.md
  - History: history.md

theme: readthedocs

markdown_extensions:
  - admonition
plugins:
  - mkapi:
    src_dirs: [omicron]

have tried python -c import omicron without error.

The error raised (by command mkdocs serve -v -a 0.0.0.0:8000):

DEBUG   -  Config value: 'markdown_extensions' = ['toc', 'tables', 'fenced_code', 'admonition'] 
DEBUG   -  Config value: 'mdx_configs' = None 
DEBUG   -  Config value: 'strict' = False 
DEBUG   -  Config value: 'remote_branch' = 'gh-pages' 
DEBUG   -  Config value: 'remote_name' = 'origin' 
DEBUG   -  Config value: 'extra' = {} 
DEBUG   -  Config value: 'plugins' = [{'mkapi': None, 'src_dirs': ['omicron']}] 

Aborted with 1 Configuration Errors!
``

[zillionare]

update:

mkapi has been installed, the version is 1.0.13. other plugins works fine. If I remove src_dirs， it can pass but will fail to build api docs

[daizutabi]

Please change the indent like below:

plugins:
  - mkapi:
      src_dirs: [omicron]

[zillionare]

sorry, my fault. Thanks!