Tranfer problem when I use Xfer button on the phone!

The phone A call B,
B answer and A speek with B,
B, throuth press Xfer button on the phone, transfer the call to phone C,
B, througth the hangup, put the connection between A e C, A speek with C.

All It’s OK, but …

If I use application map, the last step broken down.
I set the variable DYNAMIC_FEATURES=…

Thanks in advance

Best regards

Luigi