2 files changed, 7 insertions, 2 deletions
diff --git a/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/ImageDetailsWindow.java b/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/ImageDetailsWindow.java
index 05120831..17a24626 100644
--- a/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/ImageDetailsWindow.java
+++ b/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/ImageDetailsWindow.java
@@ -588,11 +588,14 @@ public class ImageDetailsWindow extends ImageDetailsWindowLayout implements UiFe
 		// Count the number of linked lectures to the image
 		int lectureCount = 0;
 		for (LectureSummary lecture : LectureCache.get(false)) {
+			if (lecture == null || lecture.imageBaseId == null)
+				continue;
 			if (lecture.imageBaseId.equals(image.imageBaseId))
 				lectureCount++;
 		}
 		linkedLectureCount.setText(Integer.toString(lectureCount));
-
+		btnShowLinkingLectures.setEnabled(lectureCount > 0);
+		
 		// set the versions of the image to the table
 		versionTable.setData(image.getVersions(), true);
 		popupItemDelete.setEnabled(ImagePerms.canAdmin(image));
diff --git a/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/LectureListWindow.java b/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/LectureListWindow.java
index f8fb7ac2..faa3d98d 100644
--- a/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/LectureListWindow.java
+++ b/dozentenmodul/src/main/java/org/openslx/dozmod/gui/window/LectureListWindow.java
@@ -488,10 +488,12 @@ public class LectureListWindow extends LectureListWindowLayout {
 	}
 
 	public void filterByImageBaseId(final String imageBaseId) {
+		if (imageBaseId == null)
+			return;
 		RowFilter<ListModel<LectureSummary>, Integer> imageFilter = new RowFilter<ListModel<LectureSummary>, Integer>() {
 			public boolean include(Entry<? extends ListModel<LectureSummary>, ? extends Integer> entry) {
 				LectureSummary lecture = lectureTable.getModelRow(entry.getIdentifier());
-				return lecture.imageBaseId.equals(imageBaseId);
+				return imageBaseId.equals(lecture.imageBaseId);
 			}
 		};
 		filterCbo.setSelectedIndex(-1);