Recv 08A2 0006 : PC->TI: Silent - Request Variable (REQ) ==> Which one?
Send 9856 0000 : TI->PC: ACK
Send 9806 000B : TI->PC: Variable Header (VAR) of the requested variable
Recv 0856 0000  : PC->TI ACK
Recv 0809 0000 :  PC->TI Ok to send the data (CTS)
<== ERROR: Link format ==>
<== ERROR: Link format ==>
Send 9856 0000  : TI->PC ACK
Send 9815 0020  : TI->PC Data associated to the requested variable (XDP).
Recv 0856 0000  : PC->TI ACK
Send 9892 0000 : TI->PC END OF TRANSMISSION

You can get this error for:
Receiving VAR / RTS: The variable name field is bigger than 17
Receiving a REQ / Directory listing: folder file name length is bigger than 8.
Receiving a REQ / Other file: Either the file name size is 0, or bigger than 17.

I suspect receiving a REQ / Type ID Byte different of 1A or 1B, and with 0 file name size.
I suspect even:

Requesting ID list
Indeed, the request is as if the TI requested the 'IDLIST' variable: Ty=22 and Nl=00.
This request works only with upgraded calculator (check if TI has been upgraded before). 

For the Checking FLASH

The protocol for checking whether the calculator AMS has been upgraded is described below.
	REQ special: 00 68 00 00.
	ACK: either 98 56 00 10 (not upgraded), either 98 56 10 04 (upgraded).

PedroM answers $1001 (ie. upgraded).
==> ticonnect may suppose it can sens an IDLIST request.