OnRowValidate will only trigger after the user leave a row. For your scenario, during OnRowValidate client side event you could check if there is certain value of the cell is prohibited and returning false to abort the operation. Here is the snippet that show how to abort the operation if the ContactTitle cell has the value of Owner1 and set the focus to ContactTitle cell:

function grdObj_OnRowValidate(rowObject)
{
    var grid = ISGetObject("WebGrid1");

    var cellName = wgGetCellByName(rowObject, "ContactTitle");
    if (cellName.cellValue == "Owner1") {
       grid.GetRowByElement(rowObject).GetCell("ContactTitle").ActivateEdit(); 
       return false;    
    }
	
	return true;
}

Sorry I might not have been too clear in my previous post. I have compiled a sample for you to make it easier to understand my problem. Please follow these steps:

1. In the log type column for row 1, select a log type of Wastage and then click on row 2. You should prompted with an alert box asking you to pick a wastage code.

2. Select a wastage code and then click on row 2.

3. Now select the log type column of row 1 again and this time select Production Count and then click row 2. This time the wastage code column should have cleared its value and you should not have received the popup message. This is the correct behaviour.

4. Now select the log type column of row 1 again and this time select Wastage again and then click on row 2. Notice this time that you did NOT get prompted with an alert box asking you to pick a wastage code. This is the problem. Everytime you pick a log type of wastgae, I need to the row to validate that a wastage code has been entered, not just the first time.

Can you please modify my sample so that the row validates every time it is modified?

Using the latest hotfix, I could not replicate the issue using the steps you describe. Please update your component to the latest build to fix the issue

I can confirm that updating the components has fixed this issue.