Font material problem: disappearing characters on Android

Hi, Can anyone help with a weird Android disappearing characters problem? our app is using some unique fonts, everything looks fine when using unity's default font material, but when using a black font material , some of the characters would be missing and a blank space would appear in their place. (e.g. the string"7018" would be "7 8"). It doesn't occur on iOS - only on Android. BTW, On first run after installing the app everything looks fine and all the characters appear as they should... the font material was created according to these instructions: http://answers.unity3d.com/questions/34465/changing-font-colour.html

Thanks !