Advanced Dragons, cannot hatch dragon egg on ipad but can on xbox

Hello. 

I get the dragon totem, summon the egg and then go get the activator.   I use the activator but it is like I am just hitting the egg and causing damage. No dragon hatches.  If I do exactly the same procedure on the xbox then the dragon hatches.  How do I hatch the egg on the ipad? 

 

Thanks for any help.