A masternode collateral is a transaction of exactly 1,000 Dash. The 1,000 Dash must be sent as a single transaction, meaning you cannot send multiple transactions to a public key that add up to 1,000 Dash.
An example of a properly funded public key with a single 1,000 Dash transaction should look like the following screenshot. Notice the amount of the first transaction is exactly 1,000.
If you are trying to commission a new masternode with Node40 and the collateral cannot be located, please confirm a proper transaction is associated with your public key. You can review the transaction on the blockchain by using the official Dash block explorer at https://explorer.dash.org/chain/Dash