Double click after pressing tab

[shelly]

I have to press tab to reach a selected button then double click on that

Here's my script but its not working:

WinActivate("Policy Decisions -- Webpage Dialog","")
Sleep(3000)
Send("{TAB}")
Send("{TAB}")
Send("{TAB}")                    // at this point its working according to my need  but double click is not working
Mouseclick("Left",510, 320, 2, 0)