Thanks for the screenshot.
The empty space that you are seeing below the last data row is expected to occur in the following case:
1) you have enabled scrolling
2) no Height or ScrollHeight is specified
In this case the default height of RadGrid's data area is 300px. If the amount of data is less than this designated height, you will see this empty space at the bottom.
You can change the height of RadGrid at runtime, if the datasource returns a small number of items. Alternatively, if RadGrid displays a small number of items most of the time, then it is better to disable scrolling or set a smaller height declaratively.
Let us know if you need more information.
the Telerik team
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