The green portal shows on the island but not on the control panel...it remains the normal portal to return home.

I am using an Asus AMD 1225B laptop with Windows 7 and Radeon HD6290 graphics ...I have emptied my cache and refreshed the page

I have a screenshot 

This happens if you do not have any portal energy cells; have you checked your inventory to make sure you have one to use?

If you've already checked and that isn't the issue then I'm not sure what will help. That's my only idea XD

That was why....I had  completely forgotten about them :( 

 I had crafted a lot of cells but  it's a long time since I checked what I had left

Thanks for reminding me :)