The sample doesn’t flow into the chamber
Especially with new (unused) sample chambers you may encounter an issue with the sample not being completely pulled through by capillary forces. In this case, it is usually helpful to lightly tap the chamber on a fixed surface.
Air bubbles in the chamber
Bubbles may form while the chamber is being filled (see the image below). This can often interfere with accurate measurement. In order to remove any bubble(s), the chamber should be rinsed out and then refilled.
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