Could Not Save Font File

I could not save the font file. I am trying to copy a glyph from a installed font file to another empty glyph that i am editing. I mapped the charater to the glyph accordingly by manually type in ($xxxx) and press ADD in Mappings, using back the same Microsoft Unicode Mapping index ($xxxx) number .

I tried on another character and this time, i use select and select a Unicode Block from the list and select a value and it works

I wonder how can i resolve this, any steps i miss out, i am a beginner
Need help, urgent. Thanks

Every time I have not been able to save a font file it has been because I also had the file open in another application like MainType.

If that is your problem, simply select another font in the other application and the ability to save should be restored.

i figured that out. Thanks!