diff --git a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/UtilityEvaluatorController.java b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/UtilityEvaluatorController.java
index 86162d8..9892ba9 100644
--- a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/UtilityEvaluatorController.java
+++ b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/UtilityEvaluatorController.java
@@ -9,6 +9,7 @@ import eu.nebulous.utilityevaluator.converter.NodeCandidateConverter;
 import eu.nebulous.utilityevaluator.model.Application;
 import eu.nebulous.utilityevaluator.model.NodeCandidateDTO;
 import eu.nebulous.utilityevaluator.model.VariableDTO;
+import eu.nebulous.utilityevaluator.model.VariableType;
 import eu.nebulous.utilityevaluator.regression.SimpleCostRegression;
 import eu.nebulouscloud.exn.core.Publisher;
 import eu.nebulouscloud.exn.core.SyncedPublisher;
@@ -47,8 +48,15 @@ public class UtilityEvaluatorController {
             }
             List<NodeCandidateDTO> convertedNodeCandidates = NodeCandidateConverter.convertToDtoList(nodeCandidates);
             List<VariableDTO> componentVariables = application.getVariables().get(component);
-            SimpleCostRegression regression = new SimpleCostRegression(component, convertedNodeCandidates, componentVariables);
-            application.getCostPerformanceIndicators().put(component, regression);
+
+            if (componentVariables.stream().filter(var -> var.getType().equals(VariableType.CPU) || var.getType().equals(VariableType.RAM)).findAny().isPresent()){
+                SimpleCostRegression regression = new SimpleCostRegression(component, convertedNodeCandidates, componentVariables);
+                application.getCostPerformanceIndicators().put(component, regression);
+            }
+            else {
+                log.warn("There are no variables for component {} = it is not possible to create any cost performance indicator!", component);
+            }
+
 
         };
         
diff --git a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/communication/exnconnector/PerformanceIndicatorSendingService.java b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/communication/exnconnector/PerformanceIndicatorSendingService.java
index 76c1675..89f0807 100644
--- a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/communication/exnconnector/PerformanceIndicatorSendingService.java
+++ b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/communication/exnconnector/PerformanceIndicatorSendingService.java
@@ -54,7 +54,7 @@ public class PerformanceIndicatorSendingService {
 
             String componentNameValidAMPL=component.replaceAll("/", "_").substring(1);
 
-            String piName = "cost_pi"+componentNameValidAMPL;
+            String piName = "cost_pi_"+componentNameValidAMPL;
 
             ObjectNode pi = performanceIndicators.addObject();
             //ObjectNode pi = performanceIndicators.withObject(piName);
diff --git a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/converter/NodeCandidateConverter.java b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/converter/NodeCandidateConverter.java
index 2dbecf4..3bacc98 100644
--- a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/converter/NodeCandidateConverter.java
+++ b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/converter/NodeCandidateConverter.java
@@ -79,7 +79,7 @@ public class NodeCandidateConverter {
                         usedNodeParameters.add(node.getCpu());
                         break;
                     case RAM:
-                    usedNodeParameters.add(Long.valueOf(node.getRam()).intValue());
+                        usedNodeParameters.add(Long.valueOf(node.getRam()).intValue());
                         break;
                     default:
                         log.debug("Variable type {} is not usable in cost performance indicators", variable.getType());
diff --git a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/regression/SimpleCostRegression.java b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/regression/SimpleCostRegression.java
index 47aa390..3d5a08f 100644
--- a/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/regression/SimpleCostRegression.java
+++ b/utility-evaluator/src/main/java/eu/nebulous/utilityevaluator/regression/SimpleCostRegression.java
@@ -10,10 +10,7 @@ import eu.nebulous.utilityevaluator.model.VariableDTO;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 
-/* TODO: comments
-this class looks good, except that the coefficient should be filtered based on the variables 
 
-*/
 @Slf4j
 public class SimpleCostRegression {
     
@@ -25,11 +22,14 @@ public class SimpleCostRegression {
 
     public SimpleCostRegression(String componentName, List<NodeCandidateDTO> nodeCandidates, List<VariableDTO> variables){
         this.componentName = componentName;
+
         this.regression = new OLSMultipleLinearRegression();
+        //double[][] argumentsForRegression = NodeCandidateConverter.convertListToDoubleArray (nodeCandidates, variables);
         regression.newSampleData(convertPricesToArray(nodeCandidates), NodeCandidateConverter.convertListToDoubleArray (nodeCandidates, variables));
         log.info("Data for component {} was loaded", componentName);
         this.coefficients = regression.estimateRegressionParameters();
         log.info("Coefficients: {}", coefficients);
+
     }
 
     private static double[] convertPricesToArray(List<NodeCandidateDTO> nodeCandidates) {