One of the causes of orange peel is the application of too much fluid and not enough atomization to break the product up into smaller droplets. It's similar to putting your finger over the end of a garden hose. Increase the atomization by using smaller fluid tips or a larger spray unit. See General Finishes comparison chart for generally recommended spray tips. Contact your spray equipment manufacturer's recommendations as well.
Another cause can be temperature. Refinishing furniture in a space that is below or above the 65-75 degrees F range can lead to problems, and a space below 55 degrees F is definitely too cold.