Chrome extension and javascript click/submit error

Fajkowsky

I am making a chrome extension and I am stuck with javascript and pressing button on page. I have site with form like this on web(isn't mine so i can't edit it):

[code][/code]

And now I automatically open page with username and password filled but now I want that button will be clicked automatically.

I have code of script:

[code]var tabID = 1;
chrome.tabs.create({index:tabID,url:"https://monostudby4frd.hisf.no:8001/",active:false,pinned:true},
function(tab) {
tabID = tab.id;
});

sleep(3000);
chrome.tabs.executeScript(null, {code:clickButton()});
sleep(3000);

chrome.tabs.getSelected(null, function(tab) {
chrome.tabs.remove(tabID);
});



function sleep(ms) {
var dt = new Date();
dt.setTime(dt.getTime() + ms);
while (new Date().getTime() < dt.getTime());
}

function clickButton() {
document.getElementById("accept").click();
}[/code]
And debugger says:

[code]Uncaught TypeError: Cannot call method 'click' of null[/code]

Thx for any help!