JetFlashM cannot play encoded wma files because Microsoft Windows Media Player 9 has a "Protect Content" option. You can solve the problem by disabling this option.
1) Select "Tools" from the menu bar.
2) Select "Options" from the drop-down menu.
3) Select the "Copy Music" tab.
4) Under "Copy" settings, make sure that the "Protect Content" box is unchecked.