Neha,
If you are using SP04 server you should be using a WPF client from SDK SP05 or higher. Either way you should probably also test with the latest version SDK SP06 PL02 which will have all the latest fixes to the WPF client.
The reason for the problem is the resolution of the device. What resolution are you running? You may need to look at creating a new version of the detail screen targeting the resolution you are running and adjust the number of rows / styles and fonts accordingly.
The WPF client does not support scrolling in a detail pane. As a result the display will shrink the row heights to accommodate the defined number of rows. As an alternative you can create a secondary Detail tab and move some of the rows to a new tab to decrease the number of rows which will increase the row height.
--Bill