Dear Br. Zamil Hasan,
Thank you for posting to the forum. It would be helpful for us to investigate if you provide a Map Maker URL to the feature in context. From what I know, rendering of a feature on Google Maps depends on the type of feature, its category and popularity across the web. Now what you're writing about might be just a rendering delay, if it is a recent edit, it may take about a week or two to properly display on the map, even though the boundary (gray colored shade) may appear immediately. There is no mistake in mapping the feature on your part from what I can speculate, but I can have a look into it if you provide a link to the feature. Thank you.