trying to invoke OCI document generator but its failing

Organization Name (Required - If you are an Oracle Partner, please provide the organization you are logging the idea on behalf of):

Worthington

Description (Required):

i am trying to implement OCI document generator functions for the reports. all the required setups are done as per https://blogs.oracle.com/apex/post/seamless-pdf-generation-with-oracle-apex-and-oci-document-generator but unable to invoke the functions using the command : fn invoke <appname> <functioname>. Please help me on this. Thank you

appname : myapp

functionname: myfunction.

and executing below command in OCI cloud shell

fn invoke myapp myfunction

it throws an errory saying application myapp doesn't found. Please let me know