pcu: Fix f_dl_block_ack_fn for Dl EGPRS data block

Change-Id: I012b18ef084df0faa4cce79c4778e793af39b199
diff --git a/pcu/GPRS_Components.ttcn b/pcu/GPRS_Components.ttcn
index 0f46490..2686ba3 100644
--- a/pcu/GPRS_Components.ttcn
+++ b/pcu/GPRS_Components.ttcn
@@ -1017,7 +1017,7 @@
 
 	/* The argument must be either a GPRS or EGPRS data block */
 	if (ischosen(dl_block.data_egprs)) {
-		rrbp_valid := true; /* always valid */
+		rrbp_valid := dl_block.data_egprs.mac_hdr.esp != '00'B;
 		rrbp := dl_block.data_egprs.mac_hdr.rrbp;
 	} else if (ischosen(dl_block.data)) {
 		rrbp_valid := dl_block.data.mac_hdr.mac_hdr.rrbp_valid;