compile source code error

[weixj2003ld]

I download World_Wind_1.4.0_Source.zip and complie it in msvc2005,and the error occur,"..\pulginSDK\confgurationLoader.c s(224,56):Compiler Error Message: CS1012: Too many characters in character literal" ,when I locate 224 line of file confgurationLoader.cs,it like this:

bbox[0].ToString().TrimEnd('?), bbox[1].ToString().TrimEnd('?), bbox[2].ToString().TrimEnd('?), bbox[3].ToString().TrimEnd('?));


I don't know why has many '?'