How can I get a hidden HtmlTableRow to display?

How can I get a hidden HtmlTableRow to display?

I am creating some html elements via server-side (C#) code. Since this is a jQuery forum, I won't show that code, but it adds a column caption row and a first row of "textboxes" that are visible; then, I add two more rows of textboxes that start off invisible. I additionally (no pun intended) have a button (with the caption "+") that should make the first invisible row visible on the first click, and the second invisible row visible on the second click. I'm trying to accomplish that with this jQuery:

  1. $(document).on("click", '[id$=btnAddFoapalRow]', function (e) {
        if ($('[id$=foapalrow3]').not(":visible")) {
            console.log('reached the foapalrow3 not visible branch');
            //        $('[id$=foapalrow3]').slideDown(); <= neither this nor the below works
            $('[id$=foapalrow3]').attr("visibility", "visible");
        }
        else if ($('[id$=foapalrow4]').not(":visible")) {
            console.log('reached the foapalrow4 not visible branch');
            $('[id$=foapalrow4]').slideDown();
        }
    });

I do see the "reached the foapalrow3 not visible branch'" log msg in the console, but neither the slideDown() nor the "visibility=visible" code does a durned thing (pardon my 1800s backwoods dialect). 

What do I need to do to visiblize foaplarow3 (and 4, as appropriate)?

Okay, for the curious / C#-heads, here's the code-behind/server-side:

  1.             foapalrow3 = new HtmlTableRow();
                foapalrow3.ID = "foapalrow3";

                var cellColIndex2 = new HtmlTableCell();
                cellColIndex2.Width = CELL_WIDTH;
                foapalrow3.Cells.Add(cellColIndex2);
                var cellColFund2 = new HtmlTableCell();
                cellColFund2.Width = CELL_WIDTH;
                foapalrow3.Cells.Add(cellColFund2);
                var cellColOrg2 = new HtmlTableCell();
                cellColOrg2.Width = CELL_WIDTH;
                foapalrow3.Cells.Add(cellColOrg2);
                var cellColAccount2 = new HtmlTableCell();
                cellColAccount2.Width = CELL_WIDTH;
                foapalrow3.Cells.Add(cellColAccount2);
                var cellColActivity2 = new HtmlTableCell();
                cellColActivity2.Width = CELL_WIDTH;
                foapalrow3.Cells.Add(cellColActivity2);
                var cellColAmount2 = new HtmlTableCell();
                cellColAmount2.Width = CELL_WIDTH;
                foapalrow3.Cells.Add(cellColAmount2);

                boxIndex2 = new TextBox()
                {
                    CssClass = "finaff-webform-field-input",
                    Width = TEXTBOX_WIDTH
                };
                cellColIndex2.Controls.Add(boxIndex2);
                boxFund2 = new TextBox()
                {
                    CssClass = "finaff-webform-field-input",
                    Width = TEXTBOX_WIDTH
                };
                cellColFund2.Controls.Add(boxFund2);
                boxOrganization2 = new TextBox()
                {
                    CssClass = "finaff-webform-field-input",
                    Width = TEXTBOX_WIDTH
                };
                cellColOrg2.Controls.Add(boxOrganization2);
                boxAccount2 = new TextBox()
                {
                    CssClass = "finaff-webform-field-input",
                    Width = TEXTBOX_WIDTH
                };
                cellColAccount2.Controls.Add(boxAccount2);
                boxActivity2 = new TextBox()
                {
                    CssClass = "finaff-webform-field-input",
                    Width = TEXTBOX_WIDTH
                };
                cellColActivity2.Controls.Add(boxActivity2);
                boxAmount2 = new TextBox()
                {
                    CssClass = "finaff-webform-field-input",
                    Width = TEXTBOX_WIDTH
                };
                cellColAmount2.Controls.Add(boxAmount2);
                foapalHTMLTable.Rows.Add(foapalrow3);
                foapalrow3.Visible = false;

The code for foapalrow4 is the same as the above for foapalrow3, except for the obvious differences. So, basically, all I need to happen on the clicking of the "+" button is to set:

            foapalrow3.Visible = false;

...but via jQuery. And this is what it looks like: