diff --git a/library/LAPDm_RAW_PT.ttcn b/library/LAPDm_RAW_PT.ttcn
index 164d31a..fe2d321 100644
--- a/library/LAPDm_RAW_PT.ttcn
+++ b/library/LAPDm_RAW_PT.ttcn
@@ -453,10 +453,11 @@
 				var RslLinkId link_id;
 				if (lpd.sacch) {
 					link_id := valueof(ts_RslLinkID_SACCH(lpd.sapi));
+					buf := f_pad_oct(enc_LapdmFrame(lpd.lapdm), 21, '2B'O);
 				} else {
 					link_id := valueof(ts_RslLinkID_DCCH(lpd.sapi));
+					buf := f_pad_oct(enc_LapdmFrame(lpd.lapdm), 23, '2B'O);
 				}
-				buf := enc_LapdmFrame(lpd.lapdm);
 				L1CTL.send(ts_L1CTL_DATA_REQ(chan_desc.chan_nr, link_id, buf));
 			}