Wi-Fi Hotspot button won't stay on. Is this because I'm already on a network?

Hi you helpful guys at Firefox. I'm still learning the capabilities of my ZTE Open, and have run into an interesting glitch. I'm already connected to my home wi-fi network, but when I try to activate the phone's own hotspot, the 'on' switch stays on for about a second, and then turns off again. My wi-fi setting then shows 'Disabled', but links immediately to my home network when I turn the switch back on. As I'm going to be abroad for a week soon, it'd be useful to have the phone's hotspot facility working when we're out of wi-fi range. I have been through your guide to setting up a hotspot, but always have the problem with the switch clicking off. TIA. Alex