If Alexa is having trouble understanding the names of the devices: 

• Do not use special characters (e.g., *(&%’#_) in the device names.
• Avoid typos or grammatical errors.
• Do not use conjunctions (e.g., and, or, etc.)
• Avoid using device names that are homophones of each other (e.g., Aaron’s Lights and Erin’s lights, etc.).

For more information on changing device names, see Change a device name in Amazon Alexa.