cards of a bg not recognized !?

[André.Bisseret]

Hello,
In a stack I have two groups behaving like backgrounds.
For one of them, if I script "go to last cd of bg "frame2" nothing  
happens.

In the message box if I ask :
there is bg "frame2"
--I get  "true"
If I ask :
there is last cd of bg "frame2"
--I get "false"
If I ask :
the number of cd of bg "frame2"
-- I get "0" ; In fact I have more than a hundred cd with this bg ?

(for the first bg all is OK)

I am lost ; please, could someone help me

Best regards from Grenoble
André