nextkeyview not working

I am developing an application in cocoa which shows a view with two NSTextfields and two NSButtons.To enable tab keystroke the next key view is set to next control(From NSTextfield1 to NSTextfield2 then from NSTextfield2 to NSButton 1 then from NSButton1 to NSButton 2 then NSButton2 to NSTextfield1).But the problem is i am able to navigate from NSTextfield1 to NSTextfield2 using tab key,the next tab navigates to NSTextfield1 instead of navigating to NSButton 1.I am not getting whats going wrong here

开发者_JAVA技巧Looking for a solution Thanks in advance

Mac OS X by default only navigates some controls. This is normal. See the Keyboard Shortcuts tab of the Keyboard pane of System Preferences for more info.