problem in radiobutton click event

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C#

C#4.0

Hi friends
I am developing window application.(patient details) In that It contains two radio button.and other controls.Fisrt radiobutton is called Existing patient. second radiobutton is called new patient. If I click first radiobutton then i need to enter only patient number to the textbox1. in the textbox1 leave event I bind data from database to other patient details. If i click second radiobutton then i need to enter all the data to patientdetails and save it. I completed this successfully. but the problem arise at when i click radiobutton1(existing patient)wrongly for new patient(radiobutton2) then I just click correct radiobutton(radiobutton2).here event for radiobutton1 occur.and make error.,same for vice versa.so how can i check with without affecting the one another