iphone touch problem when using a wall charger
 

ok so.. i have a little shop and i sell this eu wall charger

EU USB Wall Home Charger AC Adapter plug for i Phone 4G | eBay

and some people told me that the charger do problems with the iphone touch screen and i saw it myself
do somone know why its do this problem ? maybe somone know what charger i need to buy?

it is a low quality charger, I got some like that from Ebay.
Anyway I use it for a year with my old iPhone 3G without any problem.
Just cannot use my iPhone when it charging.

I have another one not original charger but it has no problem at all.
I guess it should be a better quality.

they are looking the same?