Import Rate->Life->Server error is displaying while adding a subrate to imported rate through application.

1] Login to the application on Stage environment .
2] Search a Company.
3] Navigate to Customizer>Rates.
4] Click on "Import" button the "Rate Import" window gets display.
5] Click on “Add New Rate” tab.
6] Select “Life” as a benefit template type.
7] Click on “Download File” button, entered the details in exported file.
8] Browse and Upload the file, click on "Import Rate" button.
9] Now from application add a subrate to this imported rate.

Actual Result:
Server error is displaying.
Expected Result:
Server error should not be display.