Haida Neutral Density Filter Set 77mm

Have before the gray filter and bought for my recent vacation because it went to the coast. In my opinion, the gray filter for the price (completely) are satisfactory. From other brands there is only one filter for the money. I managed very beautiful and convincing recordings - but also partially absolutely useless shots. In the latter, I have to fight with a red stripe that runs horizontally in the center and makes the image unusable. Whence comes, but I can not say unfortunately. Most often the error occurred when I photographed with the light (sun at your back). Against the light photographed enstandenkeine strip. Perhaps there are reflections between the lens and filter !? I have used the filter on my Sigma 17-50mm 2.8.
When the images controlled immediately after photographing (is not always easy on the camera screen - especially when it is just very bright) you just have to try more often to get his desired result.