Have you created your instance using the gcloud command? This is what I did to create first the template and then the instance based on it, using glcoud.
This is the full command I used:
gcloud compute instance-templates create [my-template-name] --machine-type n1-standard-4 --image-family debian-9 --accelerator type=nvidia-tesla-k80,count=4 --maintenance-policy TERMINATE --restart-on-failure --image-project debian-cloud --boot-disk-size 250GB
The template was successfully created, so I proceeded to create my instance based on that template:
gcloud compute instances create [my-instance-name] --source-instance-template [my-template-name]
Now, I was prompted this message:
Did you mean zone [europe-west1-c] for instance:
[my-instance-name] (Y/n)?
Responding yes gives me the error you got, but responding no and picking the zone you mentioned, us-west1-b successfully created the instance.
Here you have a couple of links on how to create instance templates and how to create an instance from an instance template.
Note that in the example, the template is not created with an accelerator. You can do that as done in the first snippet.