Anchor CPI invalid program argument

Question

I want to transfer some lamports (100) froma a PDA to an account. This is the Rust code:

pub fn test(ctx: Context<ApproveEscrow>) -> Result<()> {
    // PDA already initilized in another function and with 1 SOL amount
    let pda: &mut Account<ApproverAccount> = &mut ctx.accounts.pda;

    let seed: Pubkey = ctx.accounts.receiver.key();
    let bump_seed: u8 = ctx.bumps.pda;
    let signer_seeds: &[&[&[u8]]] = &[&[b"pda", seed.as_ref(), &[bump_seed]]];

    let cpi_context: CpiContext<Transfer> = CpiContext::new(
        ctx.accounts.system_program.to_account_info(),
        Transfer {
            from: pda.to_account_info(),
            to: ctx.accounts.receiver.to_account_info(),
        }
    ).with_signer(signer_seeds);

    transfer(cpi_context, 100)?;

    Ok(())
}

and this ts test code:

it("Test", async () => {    
        await program.methods
            .test()
            .accounts({ receiver: receiver.publicKey })
            .signers([ receiver ])
            .rpc();
}

Everything seems to work correctly, I logged every public keys and they are correct, yet I cannot understand why the transfer function returns: Error: failed to send transaction: Transaction simulation failed: Error processing Instruction 0: invalid program argument

I'm also sure the PDA account has enough balance to make the transfer. I think it's a signer problem but I really cannot get the problem and the error message does not help so much

Answer 1

If the program owns the PDA account a simple way to make the transfer is

  pda.sub_lamports(100)?;
  ctx.accounts.receiver.add_lamports(params100)?;