Raja (thatraja) gave you a good idea in his comment. I can explain: even though we cannot see the problem, it's clear: it is easy to screw up the layout and put some control away form view, for example.
This is the most likely reason: your control itself or its parent control can be just beyond the bound, by some reason which does not really matter. Try also this: go to the control's properties and set its location to (0, 0) and give it some arbitrary but reasonable size. If it can be covered by some other control, either try to put in on top or move to a open space.
When you play with that and can see what's going on, do the following: change your design and avoid the use of absolute positioning using Designer (absolute positioning uses some code is more reasonable). Instead, all your controls should be places in panels and docked, with the use of the properties
Dock and
Padding — all of them.
You can find my simple sample here:
how to dock button so that it can adjust with the form[
^].
Absolute positioning is evil and manual unreliable boring work. Don't do it.
Can you keep a secret? Here is a hint: most serious part of work in seriously designed UI is done without Designer, believe or not. :-)
—SA
Submit an article or tip