diff --git a/band-plan.html b/band-plan.html
index 6e24264..44faa72 100644
--- a/band-plan.html
+++ b/band-plan.html
@@ -174,7 +174,6 @@ div>label {
 					fill_comments(header);
 
 					// then fill tdata
-					let already_added = false;
 					extensions.forEach((ext) => {
 						if ((typeof ext.header === "undefined") || (ext.header == false)) {
 							add_column(row, base, header["base"]);
@@ -184,8 +183,7 @@ div>label {
 								// at single frequency 
 								if (isInRange(base.frequency, ext_start, ext_end)) {
 									add_column(row, ext, header["extension"]);
-								} else {
-									return;
+									tdata.push(row);
 								}
 							} else {
 								// frequeny range
@@ -193,9 +191,10 @@ div>label {
 								if (isInRange(base_start, ext_start, ext_end) && isInRange(base_end, ext_start, ext_end)) {
 									// base range is inside of ext range or the same
 									add_column(row, ext, header["extension"]);
+									tdata.push(row);
 								} else {
 									// base range is split by ext range
-									if (isInRange(ext_start, base_start, base_end)) {
+									if ((base_end > ext_start) && isInRange(ext_start, base_start, base_end)) {
 										// base range starts below ext range
 										let r = structuredClone(row);
 										let start = ext_start;
@@ -203,8 +202,7 @@ div>label {
 										r["frequency"] = start + "-" + end;
 										add_column(r, ext, header["extension"]);
 										tdata.push(r);
-										already_added = true;
-									} else if (isInRange(ext_end, base_start, base_end)) {
+									} else if ((ext_end > base_start) && isInRange(ext_end, base_start, base_end)) {
 										// ext range starts below base range
 										let r = structuredClone(row);
 										let start = base_start;
@@ -212,16 +210,11 @@ div>label {
 										r["frequency"] = start + "-" + end;
 										add_column(r, ext, header["extension"]);
 										tdata.push(r);
-										already_added = true;
 									}
 								}
 							}
 						}
 					});
-					if (!already_added) {
-						tdata.push(row);
-					}
-					already_added = false;
 				}
 			});