problem in selecting radio button in selenium RC

Hi, I am new bee to Selenium RC. In my current app i am using below code to slelect a radio button:

selenium.click("//table[@id='tblEventType']/tbody/tr/td");

during run time selenium RC/NUnit executed the command but in application radio button is not getting select.
I have also used:

selenium.Click("css=td.textcenter > input[type="radio"]");

but both are not working...Please replied if anyone has the solution.

If there is a only one radio button then - xpath=(//*[@class=" class name"])

Or you can go with this
//input[@name='name_attribute' and @value='value_attribute']

Or

//input[@type='radio'] / xpath=(//input[@type='radio'])

Or by position

//input[@type='radio' and position()=1]