Failed SIP Transfer to non-existing extension +1407XXXXXXX in context from-internal-xfer

The scenario is
PBX1 calls DID of PBX2
PBX2 tries to transfer the call to another DID

Call [email protected] got a SIP call transfer from caller: (REFER)!
Failed SIP Transfer to non-existing extension +1407XXXXXXX in context from-internal-xfer

we are using
FreePBX 2.9.0.9
Asterisk 1.4.21.2

anyone else has this problem?