diff --git a/output.cc b/output.cc
index f88f9d0..38c9533 100644
--- a/output.cc
+++ b/output.cc
@@ -194,19 +194,19 @@ void Output::Thread() {
 					}
 
 					outputser = new SER();
-					outputser->setWidth(outputserw);
-					outputser->setHeight(outputserh);
-					outputser->setColorID(serformat);
-					outputser->setPixelDepth(pixsize);
+					if (outputser) outputser->setWidth(outputserw);
+					if (outputser) outputser->setHeight(outputserh);
+					if (outputser) outputser->setColorID(serformat);
+					if (outputser) outputser->setPixelDepth(pixsize);
 					if (outputser->setFile((char *)outputfilename.c_str()) == -1) {
 						errormessage_display((char*)"windows-main", (char*)"Error", (char*)"Could not set output file [%s]. Error: %s", outputfilename.c_str(), strerror(errno));
 						SERStop();
 					}
-					outputser->setObserver((char *)"FIXME:read username from OS");
-					outputser->setTelescope((char *)"FIXME:not implemented yet");
-					outputser->setInstrument((char *)"FIXME:just read device from dirver");
-					outputser->setNumberOfFrames(0);
-					outputser->writeHeader();
+					if (outputser) outputser->setObserver((char *)"FIXME:read username from OS");
+					if (outputser) outputser->setTelescope((char *)"FIXME:not implemented yet");
+					if (outputser) outputser->setInstrument((char *)"FIXME:just read device from dirver");
+					if (outputser) outputser->setNumberOfFrames(0);
+					if (outputser) outputser->writeHeader();
 				}
 
 				else {
@@ -220,7 +220,7 @@ void Output::Thread() {
 					}
 				}
 
-				if (outputser != NULL) {	// we need to check in case outputser got deleted.
+				if (outputser) {	// we need to check in case outputser got deleted.
 					//
 					// write frame
 					outputser->appendFrame(inFrame.data);
diff --git a/videodev-dumpfile.cc b/videodev-dumpfile.cc
index f56f842..9e45334 100644
--- a/videodev-dumpfile.cc
+++ b/videodev-dumpfile.cc
@@ -40,6 +40,7 @@ VideoDev_Dumpfile::VideoDev_Dumpfile() {
 	inframe_size = 0;
 	inframe_maxsize = 0;
 	inframe_nexttime = 0;
+	fixedframesize = 0;
 };
 
 
@@ -359,14 +360,19 @@ int VideoDev_Dumpfile::ReadFrame() {
  */
 int VideoDev_Dumpfile::SetDevCtrl(unsigned int id, int value) {
 	std::list<VideoDevCtrl>::iterator ctrl;
-	printf ("%s:%d VideoDev_Dumpfile::SetDevCtrl Set Offset to %d   id:%d\n", __FILE__, __LINE__, value, id);
+	printf ("%s:%d VideoDev_Dumpfile::SetDevCtrl Set Offset to %d   id:%d  fixedframesize:%d\n", __FILE__, __LINE__, value, id, fixedframesize);
 
 	if (id == 1) {
 		ctrl = vidctrls.begin();
 		if (value != ctrl->value && value < ctrl->max) {
+			filepos = SIZE_DUMPHEADER + (value * (SIZE_FRAMEHEADER + fixedframesize));
 			ctrl->value = value;
-			lseek (fd, SEEK_SET, SIZE_DUMPHEADER + (value * (SIZE_FRAMEHEADER + fixedframesize)));
+			if (lseek (fd, filepos, SEEK_SET) < 0) {
+				printf ("%s:%d ******* lseek error:%s\n", __FILE__, __LINE__, strerror(errno));
+			}
 		}
+		else printf ("%s:%d could not set video position (ctrl->value:%d value:%d max:%d)\n",
+				__FILE__, __LINE__, ctrl->value, value, ctrl->max);
 	}
 	return VDEV_STATUS_OK;
 };