Trying to Generate Javadocs throws error message

[hadi4172]

Hi, when I try to use generate Javadocs , it doesn't work and always throw this error even if all my code is selected and there are many opportunities to add @return and @params
This is the error code :
{"code":"0102","msg":"Failed to invoke [generate docs], no codes were selected to generate docs!","msg_zh":"生成Java文档失败: 没有选中需要生成Java文档的代码!"}

Did someone encounter this problem ?

[jiangdequan]

Please check the usage of Generate Docs

[hadi4172]

I already read it before posting, the extension just don't work. Look the screenshots :

Same problem when selecting one line :

[jiangdequan]

I tried several times but I didn't reproduce the problem.