diff --git a/frontend/src/certs/NewRegister/ManualRegistration.tsx b/frontend/src/certs/NewRegister/ManualRegistration.tsx
index eed0e3d..7fbeead 100644
--- a/frontend/src/certs/NewRegister/ManualRegistration.tsx
+++ b/frontend/src/certs/NewRegister/ManualRegistration.tsx
@@ -21,6 +21,16 @@ export function ManualRegistration(props: {
 
     let datePicker: HTMLInputElement | undefined;
 
+    const courseHasCustomLabel = () => {
+        const courseId = selectedCourseId();
+        if (courseId === null) {
+            return false;
+        }
+
+        const course = courseMap()[courseId];
+        return course?.course_has_custom_label === true;
+    };
+
     const register: HTMLEventFn = async(ev) => {
         ev.preventDefault();
 
@@ -30,6 +40,15 @@ export function ManualRegistration(props: {
             return;
         }
 
+        if (courseHasCustomLabel() && customLabel() === "") {
+            setError("Escoge una denominación");
+
+            console.log(error());
+
+            setTimeout(() => setError(""), 5000);
+            return;
+        }
+
         const date = datePicker.value;
 
         if (subject === null) {
@@ -57,16 +76,6 @@ export function ManualRegistration(props: {
         setCustomLabel("");
     };
 
-    const courseHasCustomLabel = () => {
-        const courseId = selectedCourseId();
-        if (courseId === null) {
-            return false;
-        }
-
-        const course = courseMap()[courseId];
-        return course?.course_has_custom_label === true;
-    };
-
     return (
         <>
             <form onsubmit={register}>
@@ -112,8 +121,7 @@ export function ManualRegistration(props: {
                     />
 
                     <p
-                        class="my-2 p-1 w-fit mx-4 text-c-error inline-block"
-                        // style={{opacity: error() === "" ? "0" : "1", "user-select": "none"}}
+                        class="my-2 p-1 w-fit mx-4 text-c-error inline-block bg-c-background relative z-10"
                     >
                         {error()}&nbsp;
                     </p>