forall and endpoint/ended

The module below has 2 assumption examples (one using endpoint and one using ended()).  In each of them, I am trying to only allow responses to addresses that have already had requests made to them.

Before forall support, a stable, undriven signal was used for the index in properties like the ones below.  Now, with forall support, I'm trying to come up with a more portable and complete solution.  However, both properties fail in the compilation.  Can someone explain the "undeclared identifier"s problem?  There only seems to be a "undeclared" problem inside of ended or endpoint.

Thanks!

module test
#(
parameter
MEM_D=8,
ADDR_W=3
)
(
input clk,
input rq_valid,rs_valid,
input [ADDR_W-1:0] rq_addr,rs_addr

);

//psl endpoint rq_to_rs(const i)=
// {rq_valid & rq_addr==i;~(rs_valid & rs_addr==i)[*] ; rs_valid & rs_addr==i}
//;

//psl assume_good_rs0: assume
// forall i in {0:MEM_D-1}: always(
// {rs_valid & rs_addr==i} |->
// {rq_to_rs(i)}
//)@(posedge clk);

//psl assume_good_rs1: assume
// forall i in {0:MEM_D-1}: always(
// {rs_valid & rs_addr==i} |->
// {ended({rq_valid & rq_addr==i;~(rs_valid & rs_addr==i)[*] ; rs_valid & rs_addr==i})}
//)@(posedge clk);


endmodule

Error with module above:
$ ifv test.v -s
ifv: 05.83-s001: (c) Copyright 1995-2007 Cadence Design Systems, Inc.
file: test.v
// {ended({rq_valid & rq_addr==i;~(rs_valid & rs_addr==i)[*]rs_valid & rs_addr==i})}
                               |
ncvlog: *E,UNDIDN (test.v,27|31): 'i': undeclared identifier ?.5(IEEE)].
// {ended({rq_valid & rq_addr==i;~(rs_valid & rs_addr==i)[*]rs_valid & rs_addr==i})}
                                                       |
ncvlog: *E,UNDIDN (test.v,27|55): 'i': undeclared identifier ?.5(IEEE)].
// {ended({rq_valid & rq_addr==i;~(rs_valid & rs_addr==i)[*]rs_valid & rs_addr==i})}
                                                                                 |
ncvlog: *E,UNDIDN (test.v,27|81): 'i': undeclared identifier ?.5(IEEE)].
        module worklib.test:v
                errors: 3, warnings: 2
ncvlog: *F,NOTOPL: no top-level unit found, must have recursive instances.
ncverilog: *E,VLGERR: An error occurred during parsing.  Review the log file for errors with the code *E and fix those identified problems to proceed.  Exiting with code (status 2).
ifv: *F,EXEERR: Errors encountered, exiting FormalVerifier. Check formalverifier.log for details.

Error if assume_good_rs1 is commented out.
$ ifv test.v -s
ifv: 05.83-s001: (c) Copyright 1995-2007 Cadence Design Systems, Inc.
file: test.v
// {rq_to_rs(i)}
|
ncvlog: *E,UNDIDN (test.v,21|0): 'assume_good_rs0_forgen_0__i': undeclared identifier ?.5(IEEE)].
        module worklib.test:v
                errors: 1, warnings: 1
ncvlog: *F,NOTOPL: no top-level unit found, must have recursive instances.
ncverilog: *E,VLGERR: An error occurred during parsing.  Review the log file for errors with the code *E and fix those identified problems to proceed.  Exiting with code (status 2).
ifv: *F,EXEERR: Errors encountered, exiting FormalVerifier. Check formalverifier.log for details.