美国采购需求：荧光笔、凝胶荧光笔、闪光笔、白板笔、干擦笔、颜料眼线笔

I recently purchased three units of your liquid chalk maker, and unfortunately, they haven't worked as expected. I've noticed that the chalk is completely dried out, which makes it unusable for my needs. It's disappointing since I was looking forward to using these products. Could you please provide guidance on how to resolve this issue? Is it possible to exchange the dried-out units, or do you have any suggestions for getting them to work properly? I really appreciate your help and hope to find a solution soon, as I need these tools for my upcoming projects. Thanks for your attention!