If you are unable to submit a contract because the "Agree & Submit" button is un-clickable, confirm that all products in the contract have a minimum of 1 unit under the "Minimum # of Units" field.
Even if you have no units available in your inventory, you can enter 1 for this value. Since the Minimum # of Units is not fed to another part of Gateway, and lives only in the contract, your On-Hand Quantity and Available Quantity will not be affected.
If you are unable to submit a contract because of the above error message, there is already a contract active during some part of the time for the new contract that you would like to propose. Since Gateway does not allow overlapping contracts, you will need to contact your buyer in order to end the existing contract if you would like to submit the new contract.
If you are unable to submit your contract for a different reason, please submit a Vendor Helpdesk ticket.