windows store update error

[saimohan35]

I have already installed one app (for example skype). Now skype update came into store. I dont want to use data on my phone...
So i downloaded latest skype app again from windownphone.com on my pc....i copied that into my sd card.... i opened sd card in my store...
under the app it is showing update(it is not showing installed)... but it is not updating..... giving error 80070057.....
any possible solution ...?????