Hi dartali, using the above method will mean that your text will jump back to the beginning when you move the mouse off the button: i assume you would want it to stay wherever it had scrolled up to...if this is the case i would recommend doing this a different way:
Create your button and your text movieclip separately and drag them both on stage. Make sure there is a stop action on the first frame of the movieclip. Name the instance of the movieclip something like 'text'. Go the button actions and insert the following script
On (Roll Over)
Begin Tell Target ("/text"

Go to and Play ((GetProperty (textscroll, _currentframe )))
End Tell Target
End On
On (Roll Out)
Begin Tell Target ("/text"

Go to and Stop ((GetProperty (textscroll, _currentframe )))
End Tell Target
End On
Now Dave will doubtless jump on here and tell you how to simplify this code for use in flash 5, but i think it will still work so try it. Im waiting for 5 to arrive at the moment so im not too up on the new actionscripts.
Test your movie, what should happen is the text scrolls when you rollover the button, but stops where it is when you roll off. it should then carry on from where it left off when you roll back over the button.
Hope this helps
Nick Price
nick.price@misuk.net