How To Load A Set Of Pictureboxes That Are Created At Run Time

The code below is a very simplified version of what I'm trying to write in VB2010.BuildPictureBoxes() builds a column of 40 PictureBoxes at the left of Form1,while LoadPictureBoxes() fills the boxes with a set of green bars.if there are no other controls on Form1, the code does what I expect (builds and fills boxes). On the other hand, if I add, say, a TextBox at design time, then it throws an exception:[code]I understand what the exception means, but not the reason for it. Apparently, the way that I've set up the For loop in LoadPictures doesn't differentiate between a TextBox and a PictureBox. I don't understand why, nor do I understand how to code the loop.I've searched forums and tried any number of ways to write the loop, but nothing that I've tried is free of errors. Clearly, I'm overlooking something simple. I'm not asking for code, because I don't learn anything that way. [code]