diff --git a/app/assets/javascripts/app/models/_application_model.js.coffee b/app/assets/javascripts/app/models/_application_model.js.coffee
index a67494ef1..2d4cfca2c 100644
--- a/app/assets/javascripts/app/models/_application_model.js.coffee
+++ b/app/assets/javascripts/app/models/_application_model.js.coffee
@@ -64,17 +64,47 @@ class App.Model extends Spine.Model
     return '???'
 
   @validate: ( data = {} ) ->
-    return if !data['model'].configure_attributes
+    attributes = _.clone( data['model'].configure_attributes )
+    return if !attributes
+
+    # check params of screen if screen is requested
+    if data['screen']
+      for attribute in attributes
+        if attribute.screen
+          if attribute && attribute.screen && attribute.screen[ data['screen'] ] && !_.isEmpty(attribute.screen[ data['screen'] ])
+            for item, value of attribute.screen[ data['screen'] ]
+              attribute[item] = value
+
+    # check required_if attributes
+    for attribute in attributes
+      if attribute['required_if']
+
+        for key, values of attribute['required_if']
+
+          localValues = data['params'][key]
+          if !_.isArray( localValues )
+            localValues = [ localValues ]
+
+          match = false
+          for value in values
+            if localValues
+              for localValue in localValues
+                if value && localValue && value.toString() is localValue.toString()
+                  match = true
+          if match is true
+            attribute['null'] = false
+          else
+            attribute['null'] = true
 
     # check attributes/each attribute of object
     errors = {}
-    for attribute in data['model'].configure_attributes
+    for attribute in attributes
 
       # only if attribute is not read only
       if !attribute.readonly
 
         # check required // if null is defined && null is false
-        if 'null' of attribute && !attribute[null]
+        if 'null' of attribute && !attribute['null']
 
           # check :: fields
           parts = attribute.name.split '::'
@@ -103,16 +133,17 @@ class App.Model extends Spine.Model
 
     # return error object
     if !_.isEmpty(errors)
-      console.log 'error', 'validation vailed', errors
+      console.log 'error', 'validation failed', errors
       return errors
 
     # return no errors
     return
 
-  validate: ->
+  validate: (params = {}) ->
     App.Model.validate(
-      model: @constructor,
-      params: @,
+      model: @constructor
+      params: @
+      screen: params.screen
     )
 
   isOnline: ->
diff --git a/app/views/tests/model.html.erb b/app/views/tests/model.html.erb
new file mode 100644
index 000000000..ec93fd3aa
--- /dev/null
+++ b/app/views/tests/model.html.erb
@@ -0,0 +1,16 @@
+
+<link rel="stylesheet" href="/assets/tests/qunit-1.10.0.css">
+<script src="/assets/tests/qunit-1.10.0.js"></script>
+<script src="/assets/tests/model.js"></script>
+
+<style type="text/css">
+body {
+  padding-top: 0px;
+}
+</style>
+
+<script type="text/javascript">
+</script>
+
+<div id="qunit"></div>
+
diff --git a/config/routes/test.rb b/config/routes/test.rb
index 55406c6aa..8d2d96363 100644
--- a/config/routes/test.rb
+++ b/config/routes/test.rb
@@ -1,6 +1,7 @@
 Zammad::Application.routes.draw do
 
   match '/tests-core',      :to => 'tests#core',  :via => :get
+  match '/tests-model',     :to => 'tests#model', :via => :get
   match '/tests-form',      :to => 'tests#form',  :via => :get
   match '/tests-table',     :to => 'tests#table', :via => :get
   match '/tests/wait/:sec', :to => 'tests#wait',  :via => :get
diff --git a/test/browser/aab_unit_test.rb b/test/browser/aab_unit_test.rb
index 4446d1346..a5cc28541 100644
--- a/test/browser/aab_unit_test.rb
+++ b/test/browser/aab_unit_test.rb
@@ -24,6 +24,28 @@ class AAbUnitTest < TestCase
     ]
     browser_single_test(tests)
   end
+  def test_model
+    tests = [
+      {
+        :name     => 'start',
+        :instance => browser_instance,
+        :url      => browser_url + '/tests-model',
+        :action   => [
+          {
+            :execute => 'wait',
+            :value   => 8,
+          },
+          {
+            :execute      => 'match',
+            :css          => '.result .failed',
+            :value        => '0',
+            :match_result => true,
+          },
+        ],
+      },
+    ]
+    browser_single_test(tests)
+  end
   def test_form
     tests = [
       {