Cannot Create Candid File In Rust

I am following these instructions in the documentation to create a .did file:

I am able to run all of the commands until the last one. When I run the last command candid-extractor target/wasm32-unknown-unknown/release/backend.wasm > backend.did, I receive this error:

Error: failed to find function export get_candid_pointer`

What could be wrong?

You probably overlooked some previous steps.

Please make sure that the ic-cdk dependency in Cargo.toml is v0.11.0 or above.

And make sure that you have this line ic_cdk::export_candid!(); at the end of the canister source code.