After writing the following code in Flex:
[Embed(source="./assets/fonts/fonts.swf", fontName="Minion Pro")]
private var minionProRegular:Class;
I saw this error:
Multiple markers at this line:
-Unable to transcode ./assets/fonts/fonts.swf.
-font 'Minion Pro' with normal weight and regular style not found
The reason of this error message were the text boxes contained within the swf file that contains embedded fonts.
Solution:
Remove visual objects from Flash CS5 file with embedded fonts.
UPDATE:
More information about this problem can be found here