View the list of Sample Business Letters Notice of Inability to Fill Order Disclaimer: Be aware that some of these sample letters have legal, financial, or other implications. If you are not sure about the use of any letter, consult with an appropriate professional first. Notice of Inability to Fill Order Dear We have received your Purchase Order Number (number), dated (date). We regret to inform you that said order cannot be filled at this time due to the following reason: Should you care to discuss this matter further, please feel free to contact me at the above number. We look forward to your future orders and are ready to assist you in any way possible.