I am using the latest version of Collector with an iPad Air (iOS 9.2.1), and an Arrow 100 external receiver. I am using a offline map and everything seems to be fine. When I try to add a point in a layer called "locate" and then hit the submit button, I get an error saying "The shape must have a Z value". Using a different layer, I can gather a point and submit it with no problem. If I delete the offline map, and then use the map with data access, I can gather the point in the layer "locate" and submit it without any problems. I do not have any requirement to gather a z value. I'm not even sure what this "Z" pertains to. I assume an elevation maybe. I wouldn't even know how to require this. I uploaded this layer from Arcmap 10.3 Basic several months ago and haven't changed anything. I can't say if this error would have been there since the original upload or not. We are new to Collector so I'm not sure if anyone has tried taking a point in this layer up till now, or not. Any thoughts? Would I just be best to delete the layer and upload it again?