It was great experience to find out the solution, We don't need to add aplpha value to top shelf image but we should need two different images with sizes.
Top Shelf: 1920 x 720
Top Shelf Wide: 2320 x 720
The problem was:
I have created new App icon and launch image and its giving by default with name of "Brand Assets"

Then we have added all required images and tried to upload into app store finally we got this issue. To rectify this we have changed name Brand Assets into "App Icon & Top Shelf Image"
In general tab it was selected App Icon & Top Shelf Image but asset does not contain with that name.
Finally issues went away.