TextFormat and tweened text

has anybody been able to apply a TextFormat object with a change of font to a TextField in a MovieClip that is going to tween? I’ve been trying without success. What happens is that the symbol disapears if you apply alpha tweens or tweens that “flip” or rotate. However I have noticed some interesting points; Color changes to the TextField and things like bold etc work fine.Its font that causes problems. Also with tweens Scaling works ok as does simple movement. However certain tweens which unfortunately I have to use create problems. My goal for this is to develop a customisable “Text Tweening” Component so any help appreciated because at the moment the user is stuck with the fonts I specify.