What do I do if I go to walk a dog that doesn't want to go out?

I have a repeat customer that I had a meet and greet as well as two separate walks with her dog. Today when I went, the dog wasn't at the door like usual. She seemed kind of skittish but also playful. I couldn't get her to go out because she kept on running around the whole house. I gave her treats but she still wouldn't let me take her. The other times I walked her she was totally fine and ready to go! It is rainy today, could that have something to do with it? What do I do in this situation? I'm supposed to walk her again and want to make sure she isn't scared of me.