diff --git a/src/main/java/teetime/framework/AbstractStage.java b/src/main/java/teetime/framework/AbstractStage.java
index bc6a244aa1f329b878b5dfe68e4dc40fb7690804..06b1b77210a2b3bad5831307cbf3e482d792ca12 100644
--- a/src/main/java/teetime/framework/AbstractStage.java
+++ b/src/main/java/teetime/framework/AbstractStage.java
@@ -119,7 +119,8 @@ public abstract class AbstractStage extends Stage {
 
 	@Override
 	public void validateOutputPorts(final List<InvalidPortConnection> invalidPortConnections) {
-		for (OutputPort<?> outputPort : this.getOutputPorts()) {
+		// for (OutputPort<?> outputPort : this.getOutputPorts()) {
+		for (OutputPort<?> outputPort : this.outputPortList) {
 			final IPipe pipe = outputPort.getPipe();
 			if (null != pipe) { // if output port is connected with another one
 				final Class<?> sourcePortType = outputPort.getType();
diff --git a/src/main/java/teetime/framework/Analysis.java b/src/main/java/teetime/framework/Analysis.java
index 7d80f166e90d3dea3ac0ed8bb664ba6aae095df6..9645269eaf9f1551bbb4d9e4e8eaa5653b3a659e 100644
--- a/src/main/java/teetime/framework/Analysis.java
+++ b/src/main/java/teetime/framework/Analysis.java
@@ -33,13 +33,13 @@ public class Analysis implements UncaughtExceptionHandler {
 	private final Collection<Pair<Thread, Throwable>> exceptions = new ConcurrentLinkedQueue<Pair<Thread, Throwable>>();
 
 	/**
-	 * Creates a new {@link Analysis} that initially validates the port connections.
+	 * Creates a new {@link Analysis} that skips validating the port connections.
 	 *
 	 * @param configuration
 	 *            to be used for the analysis
 	 */
 	public Analysis(final AnalysisConfiguration configuration) {
-		this(configuration, true);
+		this(configuration, false);
 	}
 
 	public Analysis(final AnalysisConfiguration configuration, final boolean validationEnabled) {
diff --git a/src/main/java/teetime/framework/validation/InvalidPortConnection.java b/src/main/java/teetime/framework/validation/InvalidPortConnection.java
index dbe36d53bca2c90a1d85c651e58c7ac13b3858fe..19ea3a4526242234ed87655e735cbe9dd24177f3 100644
--- a/src/main/java/teetime/framework/validation/InvalidPortConnection.java
+++ b/src/main/java/teetime/framework/validation/InvalidPortConnection.java
@@ -24,9 +24,9 @@ public class InvalidPortConnection {
 
 	@Override
 	public String toString() {
-		final String sourcePortTypeName = (this.sourcePort.getType() == null) ? null : this.sourcePort.getType().getName();
-		final String targetPortTypeName = (this.targetPort.getType() == null) ? null : this.targetPort.getType().getName();
-		return sourcePortTypeName + " != " + targetPortTypeName;
+		final String sourcePortTypeName = (this.sourcePort.getType() == null) ? "null" : this.sourcePort.getType().getName();
+		final String targetPortTypeName = (this.targetPort.getType() == null) ? "null" : this.targetPort.getType().getName();
+		return "Source port type does not match target port type: " + sourcePortTypeName + " != " + targetPortTypeName;
 	}
 
 }