Assembly requires location to function, but no locations exist in drop box

Hello. My company has several assembly items with BOMs uploaded. They are not often utilized and I've suggested we start. When attempting to "build" an assembly, I am unable to select a location (which is a required field)... perhaps they we're set up incorrectly? Or maybe I am not doing something right. I did not see step by step instructions on Assemblies. Any assistance would be greatly appreciated.