Problem....no update, no de-install, no app....but request of update from App Store.....

Hi,
I have had the app on my ipad2, then I wanted to remove it, and now I cant install it anymore. App Store says to me that it is already installed and show to me the app in the update page...like I should update it but, in the reality it is not possible because there is not the button to update the app (thats right the app is no longer on the iPad). So Im stacked in the position where I cant update, I cant use, I cant remove and the App Store says to me that I should update it.
Thatnx for your help.
Raffaello

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