[vty_interface.c]: Warn if no BTS could be allocated
diff --git a/openbsc/src/vty_interface.c b/openbsc/src/vty_interface.c
index 2654447..76598d3 100644
--- a/openbsc/src/vty_interface.c
+++ b/openbsc/src/vty_interface.c
@@ -1324,8 +1324,11 @@
 	} else 
 		bts = gsm_bts_num(gsmnet, bts_nr);
 
-	if (!bts)
+	if (!bts) {
+		vty_out(vty, "%% Unable to allocate BTS %u%s",
+			gsmnet->num_bts, VTY_NEWLINE);
 		return CMD_WARNING;
+	}
 
 	vty->index = bts;
 	vty->node = BTS_NODE;