I have setup my C# project to use the Antlr4 build targets and extension for compiling the g4 grammer. However, when I build I am getting the following errors. Any thoughts?

```
Error   1   The name 'HIDDEN' does not exist in the current context C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   131 22  oracle
Error   2   The name 'HIDDEN' does not exist in the current context C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   136 22  oracle
Error   4   The name 'HIDDEN' does not exist in the current context C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   145 22  oracle
Error   5   'Antlr4.Runtime.ICharStream' does not contain a definition for 'LA' and no extension method 'LA' accepting a first argument of type 'Antlr4.Runtime.ICharStream' could be found (are you missing a using directive or an assembly reference?)   C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   156 25  oracle
Error   6   'Antlr4.Runtime.ICharStream' does not contain a definition for 'LA' and no extension method 'LA' accepting a first argument of type 'Antlr4.Runtime.ICharStream' could be found (are you missing a using directive or an assembly reference?)   C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   156 44  oracle
Error   7   'Antlr4.Runtime.ICharStream' does not contain a definition for 'LA' and no extension method 'LA' accepting a first argument of type 'Antlr4.Runtime.ICharStream' could be found (are you missing a using directive or an assembly reference?)   C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   156 64  oracle
Error   8   'Antlr4.Runtime.ICharStream' does not contain a definition for 'LA' and no extension method 'LA' accepting a first argument of type 'Antlr4.Runtime.ICharStream' could be found (are you missing a using directive or an assembly reference?)   C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Lexer.cs   156 84  oracle
Error   9   The name 'EOF' does not exist in the current context    C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Parser.cs  920 23  oracle
Error   10  'oracle.Verilog2001Parser' does not contain a definition for 'EOF'  C:\gNOSIS\Oracle\Software\oracle\oracle\obj\x64\Debug\Verilog2001Parser.cs  875 66  oracle

```