LMS-1563 bugfix: allow to see merged channels

SVN: 16538

screening/source/java/ch/systemsx/cisd/openbis/plugin/screening/client/web/client/application/detailviewers/WellContentDialog.java

@@ -273,7 +273,8 @@ public class WellContentDialog extends Dialog
         {
             return new Text("Incorrect well code.");
         }
-        if (images.getImageParameters().getChannelsNames().contains(channel) == false)
+        if (images.getImageParameters().getChannelsNames().contains(channel) == false
+                && channel.equals(ScreeningConstants.MERGED_CHANNELS) == false)
         {
             return new Text("No images available for this channel.");
         }