Coupons add-on not loading correctly, deactivating itself.

Hi Guys,

I am running through some tests for a Ecommerce website, to choose which e Ecommerce plugin to use.

After running through the basic set up, I went to activate the coupons add-on and configure the settings. However, the settings page is completely blank, and when you go back to the add-on page to re click on the settings link, one finds the coupons add-on had deactivated itself.

I have attached a screen shots of the sequence.

Looking at the debug log there are no entries, any ideas?