Not able to insert a record in a list using REST

My app has a list

This is the code which I have written to insert a record in this list

function test() {
    var listUrl = appWebUrl + "/_api/web/lists/getbytitle('BookCatalog')/items";
    var itemType = GetItemTypeForListName('BookCatalog');
    var item = new Object();
    item.type = itemType;
    var reco = {
        __metadata: item,
        Title: "Hellojhjkhk",
        Category1: "Worldjjlk",
        ISBN10: "123457868",
        ISBN13: "12345897979",
        Image: "http://ts2.mm.bing.net/th?id=H.4919052866749229&pid=1.7&w=216&h=188&c=7&rs=1"
    };
    console.log(JSON.stringify(reco));
    $.ajax({
        url: listUrl,
        type: "POST",
        contentType: "application/json;odata=verbose",
        data: JSON.stringify(reco),
        headers: { "Accept": "application/json; odata=verbose", "X-RequestDigest": $("#__REQUESTDIGEST").val() },
        success: function (data) { console.log("+++ insert success ++++") },
        error: function (data, errorCode, errorMessage) {
            console.log("+++ insert fail ++++");
            console.log(data.responseText);
            showError(errorMessage);
        }
    });
}
function GetItemTypeForListName(name) {
    return "SP.Data." + name.charAt(0).toUpperCase() + name.slice(1) + "ListItem";
}

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