diff --git a/build/api/core/Checker.php b/build/api/core/Checker.php
index 02d631b..108cb3e 100755
--- a/build/api/core/Checker.php
+++ b/build/api/core/Checker.php
@@ -124,7 +124,7 @@
 
 				// Boolean
 				case 'boolean':
-					return $checker && is_bool($value);
+					return $checker && ( is_bool($value) || $value === 'false' || $value === 'true' );
 					break;
 
 				// Objet non vide
diff --git a/build/api/module/ProfessorController.php b/build/api/module/ProfessorController.php
index b8b78e6..0be6192 100644
--- a/build/api/module/ProfessorController.php
+++ b/build/api/module/ProfessorController.php
@@ -84,8 +84,14 @@ class ProfessorController{
 		/** @var professor $prof_repo */
 		$prof_repo = Repo::getRepo('professor');
 
+		/* (1) Check if professor already exists */
+		$exists = $prof_repo->exists($lastName, $firstName);
 
-		/* (1) Dispatch to the repo */
+		/* (2) If found -> already exists */
+		if( !is_null($exists) )
+			return ['error' => new Error(Err::AlreadyExists)];
+
+		/* (3) Else try to create */
 		$repo_rtn = $prof_repo->create(
 			$lastName,
 			$firstName,
@@ -93,15 +99,16 @@ class ProfessorController{
 			$hoursToDo,
 			$initials,
 			$isAdmin,
-			$casLogin
+			is_null($casLogin) ? "" : $casLogin
 		);
 
 
-		/* (2) If repo error -> return it */
+		/* (4) If repo error -> return it */
 		if( is_null($repo_rtn) )
 			return ['error' => new Error(Err::RepoError)];
 
-		/* (3) Else return UID */
+
+		/* (5) Else return UID */
 		return ['created_uid' => $repo_rtn];
 
 	}
diff --git a/build/error/core/Error.php b/build/error/core/Error.php
index 3aeb804..2ff7d0b 100755
--- a/build/error/core/Error.php
+++ b/build/error/core/Error.php
@@ -76,9 +76,10 @@
 				case Err::UncallableModule:    return $this->UncallableModule();    break;
 				case Err::UncallableMethod:    return $this->UncallableMethod();    break;
 				case Err::UnknownHttpMethod:   return $this->UnknownHttpMethod();   break;
-				case Err::ConfigError:         return $this->ConfigError();        break;
+				case Err::ConfigError:         return $this->ConfigError();         break;
 				case Err::MissingParam:        return $this->MissingParam();        break;
 				case Err::WrongParam:          return $this->WrongParam();          break;
+				case Err::WrongDefaultParam:   return $this->WrongDefaultParam();   break;
 				case Err::ModuleError:         return $this->ModuleError();         break;
 				case Err::PDOConnection:       return $this->PDOConnection();       break;
 				case Err::WrongPathRepo:       return $this->WrongPathRepo();       break;
@@ -160,6 +161,14 @@
 					return 'wrong param \''.$this->arguments[0].'\'';
 			else
 				return 'wrong param';
+		}private function WrongDefaultParam(){
+			if(	count($this->arguments) > 0 )
+				if(	count($this->arguments) > 1 )
+					return 'wrong default param \''.$this->arguments[0].'\' expected to be of type \''.$this->arguments[1].'\'';
+				else
+					return 'wrong default param \''.$this->arguments[0].'\'';
+			else
+				return 'wrong param';
 		}private function ModuleError(){
 			return 'module error';
 		}private function PDOConnection(){