Missing values in dropdown

I have开发者_Go百科 encountered a problem using a janus grid. I have created a dropdown and bound a datasource to it. The datasource is filled with data, but when I use the dropdown it doesn't show any values. I can choose one of the hidden values and the cell text is updated fine. It looks like the values are there but for some reason I can't see it. I have already checked the font properties.

What might be causing this?