diff --git a/SpigotCore_Main/src/de/steamwar/command/SWCommand.java b/SpigotCore_Main/src/de/steamwar/command/SWCommand.java
index d1bcdb1..2cd1a0a 100644
--- a/SpigotCore_Main/src/de/steamwar/command/SWCommand.java
+++ b/SpigotCore_Main/src/de/steamwar/command/SWCommand.java
@@ -19,6 +19,7 @@
 
 package de.steamwar.command;
 
+import org.bukkit.Bukkit;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandSender;
 
@@ -28,6 +29,7 @@ import java.lang.reflect.Parameter;
 import java.util.*;
 import java.util.function.BiConsumer;
 import java.util.function.IntPredicate;
+import java.util.logging.Level;
 
 public abstract class SWCommand {
 
@@ -94,9 +96,11 @@ public abstract class SWCommand {
                     return;
                 }
                 if (!parameters[parameters.length - 1].isVarArgs()) {
+                    Bukkit.getLogger().log(Level.WARNING, "The method '" + method.toString() + "' is lacking the varArgs parameters as last Argument");
                     return;
                 }
                 if (parameters[parameters.length - 1].getType().getComponentType() != String.class) {
+                    Bukkit.getLogger().log(Level.WARNING, "The method '" + method.toString() + "' is lacking the varArgs parameters of type '" + String.class.getTypeName() + "' as last Argument");
                     return;
                 }
                 commandHelpSet.add(new SubCommand(this, method, anno.value()));
@@ -121,7 +125,10 @@ public abstract class SWCommand {
                     if (mapper != null) {
                         name = mapper.value();
                     }
-                    if (!SWCommandUtils.MAPPER_FUNCTIONS.containsKey(name)) return;
+                    if (!SWCommandUtils.MAPPER_FUNCTIONS.containsKey(name)) {
+                        Bukkit.getLogger().log(Level.WARNING, "The parameter '" + parameter.toString() + "' is using an unsupported Mapper of type '" + name + "'");
+                        return;
+                    }
                 }
                 commandSet.add(new SubCommand(this, method, anno.value()));
             });
@@ -136,12 +143,15 @@ public abstract class SWCommand {
 
         Parameter[] parameters = method.getParameters();
         if (!parameterTester.test(parameters.length)) {
+            Bukkit.getLogger().log(Level.WARNING, "The method '" + method.toString() + "' is lacking parameters or has too many");
             return;
         }
         if (firstParameter && !CommandSender.class.isAssignableFrom(parameters[0].getType())) {
+            Bukkit.getLogger().log(Level.WARNING, "The method '" + method.toString() + "' is lacking the first parameter of type '" + CommandSender.class.getTypeName() + "'");
             return;
         }
         if (returnType != null && method.getReturnType() != returnType) {
+            Bukkit.getLogger().log(Level.WARNING, "The method '" + method.toString() + "' is lacking the desired return type '" + returnType.getTypeName() + "'");
             return;
         }
         consumer.accept(anno, parameters);
diff --git a/SpigotCore_Main/src/de/steamwar/command/SubCommand.java b/SpigotCore_Main/src/de/steamwar/command/SubCommand.java
index 640bdbf..8321196 100644
--- a/SpigotCore_Main/src/de/steamwar/command/SubCommand.java
+++ b/SpigotCore_Main/src/de/steamwar/command/SubCommand.java
@@ -94,9 +94,9 @@ class SubCommand {
             objects[0] = commandSenderFunction.apply(commandSender);
             method.setAccessible(true);
             method.invoke(swCommand, objects);
-        } catch (IllegalArgumentException | IllegalAccessException e) {
+        } catch (IllegalAccessException | RuntimeException e) {
             throw new SecurityException(e.getMessage(), e);
-        } catch (InvocationTargetException | RuntimeException e) {
+        } catch (InvocationTargetException e) {
             Bukkit.getLogger().log(Level.INFO, e.getMessage(), e);
             return false;
         }
@@ -105,23 +105,23 @@ class SubCommand {
 
     List<String> tabComplete(CommandSender commandSender, String[] args) {
         if (!varArgs && args.length < arguments.length - 1) {
-            return Collections.emptyList();
+            return null;
         }
         List<String> argsList = new LinkedList<>(Arrays.asList(args));
         for (String value : subCommand) {
             String s = argsList.remove(0);
             if (argsList.isEmpty()) return Collections.singletonList(value);
-            if (!value.equals(s)) return Collections.emptyList();
+            if (!value.equals(s)) return null;
         }
         for (TypeMapper<?> argument : arguments) {
             String s = argsList.remove(0);
             if (argsList.isEmpty()) return argument.tabCompletes(commandSender, Arrays.copyOf(args, args.length - 1), s);
             try {
                 if (argument.map(s) == null) {
-                    return Collections.emptyList();
+                    return null;
                 }
             } catch (Exception e) {
-                return Collections.emptyList();
+                return null;
             }
         }
         if (varArgs && !argsList.isEmpty()) {
@@ -130,13 +130,13 @@ class SubCommand {
                 if (argsList.isEmpty()) return arguments[arguments.length - 1].tabCompletes(commandSender, Arrays.copyOf(args, args.length - 1), s);
                 try {
                     if (arguments[arguments.length - 1].map(s) == null) {
-                        return Collections.emptyList();
+                        return null;
                     }
                 } catch (Exception e) {
-                    return Collections.emptyList();
+                    return null;
                 }
             }
         }
-        return Collections.emptyList();
+        return null;
     }
 }