My Invisalign doesn't work and my diastema keeps appearing. What should I do next?

I got my braces removed a week back and got my retainers four days back..during my treatment I developed mid line diastema..my dentist tried using power chains to close the gap but as soon as he would remove the power chain the gap would reapear in few days..now my braces are removed and the gap has reappeared on second day ..I got my retainers on the third day..my dentist told me that it invisalign would close my gap but I honestly feel no difference after four days..what should I do next?