Why my Solana program encounter this error: Provided seeds do not result in a valid address

Question

I am new to programming in Solana. Here I want to apply the MPL core for my application. There is a feature that a MPL core asset can bind with an "oracle account". This oracle account should be a PDA that containing information for the life cycle of the MPL Core. (correct me if I say it wrong.)

Here is the code:

    // https://solana.com/docs/core/pda
    // https://github.com/metaplex-foundation/mpl-core/blob/main/clients/js/src/plugins/lifecycleChecks.ts#L42
    // let oracle_plugin = Pubkey::from_str("6qjMzebX6DBJMbrNPk2UejZSkF7i8H5Nc5gbQAgKw7ay").unwrap();
    let oracle_plugin = LIFE_HELPER_ID;
    external_plugin_adapters.push(ExternalPluginAdapterInitInfo::Oracle(OracleInitInfo {
        base_address: oracle_plugin,
        init_plugin_authority: None,
        lifecycle_checks: vec![(
            HookableLifecycleEvent::Transfer,
            ExternalCheckResult { flags: 4 }, // CAN_REJECT
        )],
        // https://github.com/metaplex-foundation/mpl-core/blob/7d82981e9be90592579055cfc8f4006aeeff28c3/programs/mpl-core/src/plugins/external_plugin_adapters.rs#L467
        base_address_config: Some(ExtraAccount::PreconfiguredAsset {
            // TODO: unused parameters?
            is_signer: false,
            is_writable: false,
        }),
        results_offset: Some(ValidationResultsOffset::Anchor),
    }));

The PreconfiguredAsset should tell that the PDA should be created from the seeds "mpl-core" and the public key of the Core Asset. Hence, I call another function to create the PDA.

    let life_helper_program = ctx.accounts.life_helper_program.to_account_info();
    let life_helper_cpi_accounts = LifeHelperAccounts4Init {
        signer: ctx.accounts.payer.to_account_info(),
        payer: ctx.accounts.payer.to_account_info(),
        asset: ctx.accounts.asset.to_account_info(),
        oracle_account: ctx.accounts.life_helper_pda.to_account_info(),
        system_program: ctx.accounts.system_program.to_account_info(),
    };
    // https://stackoverflow.com/questions/70675404/cross-program-invocation-with-unauthorized-signer-or-writable-account
    // https://solana.com/developers/guides/getstarted/how-to-cpi-with-signer
    let payer_seed = ctx.accounts.payer.to_account_info().key();
    let asset_seed = ctx.accounts.asset.to_account_info().key();
    // let bump_seed = ctx.accounts.life_helper_pda.to_account_info().key();
    let bump_seed = &[args.bump];
    let signer_seeds: &[&[&[u8]]] = &[&[
        payer_seed.as_ref(),
        asset_seed.as_ref(),
        b"mpl-core",
        bump_seed,
    ]];
    msg!("signer_seeds: {:?}", signer_seeds);
    let life_helper_ctx =
        CpiContext::new(life_helper_program, life_helper_cpi_accounts).with_signer(signer_seeds);
    life_helper::cpi::initialize(
        life_helper_ctx,
        LifeHelperArgs4Init {
            transfer_limit: args.transfer_limit,
        },
    )?;

Another piece of code that is defined in life_helper program:

#[derive(Accounts)]
pub struct Accounts4Init<'info> {
    pub signer: Signer<'info>,
    #[account(mut)]
    pub payer: Signer<'info>,

    /// CHECK: this account will not be checked
    pub asset: UncheckedAccount<'info>,

    #[account(init, payer = payer, space = Validation::INIT_SPACE, seeds = [b"mpl-core", asset.key().as_ref()], bump)]
    pub oracle_account: Account<'info, Validation>,
    pub system_program: Program<'info, System>,
}

And this is how I did to create the PDA id:

let asset = Keypair.generate();
const [life_helper_pda, life_helper_seed] = PublicKey.findProgramAddressSync(
  [
    anchor.utils.bytes.utf8.encode('mpl-core'),
    asset.publicKey.toBuffer(),
  ],
  lifeHelperProg.programId
)

The problem is when I test calling the function it sometimes give me the error:

Message: Transaction simulation failed: Error processing Instruction 0: Program failed to complete. 
Logs: 
[
  "Program B28UKH17RsMkqA9n3YbviRMny9yeiBdM7pzjT9LK1JZ invoke [1]",
  "Program log: Instruction: CreateTicketV1",
  "Program B28UKH17RsMkqA9n3YbviRMny9yeiBdM7pzjT9LK1JZ consumed 6901 of 200000 compute units",
  "Program B28UKH17RsMkqA9n3YbviRMny9yeiBdM7pzjT9LK1JZ failed: Could not create program address with signer seeds: Provided seeds do not result in a valid address"
]. 
Catch the `SendTransactionError` and call `getLogs()` on it for full details.

And sometimes it is ok to run. I don't know what lead to this problem and why sometime s it works sometimes it don't.

It should give correct each time I call the function.

This is my full code: https://github.com/WangWilly/solana-poneglyph/tree/master/contract