diff --git a/src/TensorFlowNET.Core/Train/AdamOptimizer.cs b/src/TensorFlowNET.Core/Train/AdamOptimizer.cs
index e4e01c77..06f51352 100644
--- a/src/TensorFlowNET.Core/Train/AdamOptimizer.cs
+++ b/src/TensorFlowNET.Core/Train/AdamOptimizer.cs
@@ -46,7 +46,8 @@ namespace Tensorflow.Train
             var lr = (lr_t * math_ops.sqrt(1 - beta2_power) / (1 - beta1_power));
             var m = get_slot(var, "m");
             var m_scaled_g_values = grad * (1 - beta1_t);
-            var m_t = state_ops.assign(m, m * beta1_t, use_locking: _use_locking);
+            var mul = m * beta1_t;
+            var m_t = state_ops.assign(m, mul, use_locking: _use_locking);
             with(ops.control_dependencies(new[] { m_t }), delegate
             {
                 m_t = scatter_add(m, indices, m_scaled_g_values);
@@ -88,9 +89,15 @@ namespace Tensorflow.Train
 
         public override void _prepare()
         {
-            //copied from GradientDescentOptimizer
-            LearningRate = _call_if_callable(LearningRate);
-            LearningRateTensor = ops.convert_to_tensor(LearningRate, name: "learning_rate");
+            var lr = _call_if_callable(_lr);
+            var beta1 = _call_if_callable(_beta1);
+            var beta2 = _call_if_callable(_beta2);
+            var epsilon = _call_if_callable(_epsilon);
+
+            _lr_t = ops.convert_to_tensor(lr, name: "learning_rate");
+            _beta1_t = ops.convert_to_tensor(beta1, name: "beta1");
+            _beta2_t = ops.convert_to_tensor(beta2, name: "beta2");
+            _epsilon_t = ops.convert_to_tensor(epsilon, name: "epsilon");
         }
     }
 }
diff --git a/src/TensorFlowNET.Core/Train/GradientDescentOptimizer.cs b/src/TensorFlowNET.Core/Train/GradientDescentOptimizer.cs
index f545d859..d69228d6 100644
--- a/src/TensorFlowNET.Core/Train/GradientDescentOptimizer.cs
+++ b/src/TensorFlowNET.Core/Train/GradientDescentOptimizer.cs
@@ -26,14 +26,13 @@ namespace Tensorflow.Train
         public GradientDescentOptimizer(float learning_rate, bool use_locking = false, string name = "GradientDescent") 
             : base(learning_rate, use_locking, name)
         {
-            LearningRate = learning_rate;
-            LearningRateTensor = null;
+            _lr = learning_rate;
         }
 
         public override void _prepare()
         {
-            LearningRate = _call_if_callable(LearningRate);
-            LearningRateTensor = ops.convert_to_tensor(LearningRate, name: "learning_rate");
+            var lr = _call_if_callable(_lr);
+            _lr_t = ops.convert_to_tensor(lr, name: "learning_rate");
         }
     }
 }
diff --git a/src/TensorFlowNET.Core/Train/Optimizer.cs b/src/TensorFlowNET.Core/Train/Optimizer.cs
index d5c1f5c1..c7a31b9d 100644
--- a/src/TensorFlowNET.Core/Train/Optimizer.cs
+++ b/src/TensorFlowNET.Core/Train/Optimizer.cs
@@ -23,8 +23,10 @@ namespace Tensorflow
 
         string _name;
         public string Name => _name;
-        public float LearningRate { get; set; }
-        public Tensor LearningRateTensor { get; set; }
+        protected float _lr;
+        public float LearningRate => _lr;
+        protected Tensor _lr_t;
+        public Tensor LearningRateTensor => _lr_t;
         public bool _use_locking;
         public Dictionary<string, Dictionary<string, RefVariable>> _slots;
         public Dictionary<string, RefVariable> _non_slot_dict;
@@ -38,7 +40,7 @@ namespace Tensorflow
 
             _name = name;
             _use_locking = use_locking;
-            LearningRate = learning_rate;
+            _lr = learning_rate;
             // Dictionary of slots.
             _slots = new Dictionary<string, Dictionary<string, RefVariable>>();
             _non_slot_dict = new Dictionary<string, RefVariable>();
@@ -302,7 +304,7 @@ namespace Tensorflow
 
         protected RefVariable _get_non_slot_variable(string name, Graph graph = null)
         {
-            var key = $"{graph.graph_key}.{name}";
+            var key = $"{name}.{graph.graph_key}";
             var non_slot = _non_slot_dict.ContainsKey(key) ? _non_slot_dict[key] : null;
 
             return non_slot;
diff --git a/src/TensorFlowNET.Core/Variables/state_ops.cs b/src/TensorFlowNET.Core/Variables/state_ops.cs
index 4022e1dc..22894fe0 100644
--- a/src/TensorFlowNET.Core/Variables/state_ops.cs
+++ b/src/TensorFlowNET.Core/Variables/state_ops.cs
@@ -36,8 +36,8 @@ namespace Tensorflow
                     validate_shape: validate_shape,
                     use_locking: use_locking,
                     name: name);
-            else
-                throw new NotImplementedException("state_ops.assign");
+            throw new NotImplementedException("state_ops.assign");
+            //return @ref.assign(value, name: name);
         }
 
         public static Tensor assign_sub(RefVariable @ref,