Ok so I bought a 20 dollar playstation network card and activated it on my american account.?
Unfortunately, no. Sorry... I heard that the PSN cards are region coded.
"PSN Card money cannot be transferred from a user account to another one, including on the same machine." Also on Wikipedia: "SCEA originally announced that the cards would be available in Spring 2008. The cards have been limited to Meijer stores and select military bases. As of September 2008, PlayStation Network Cards are available at Blockbuster, Rite-Aid, and 7-Eleven stores across the United States. As of October 2008 they are available in Wal-Mart, Best Buy, and Target stores across the United States. The PlayStation Network Cards are available in $20 and $50 denominations.The network cards are not available in PAL standard regions (Europe, Australasia, Middle East, etc.) where credit card remains the only way to buy PlayStation Store contents. However as with North America, in PlayStation 3 firmware update 2.0, the option was made available from the Transaction Management menu. "Tickets" code system is replaced by an upcoming feature known as "Promotion Code"."