The Readme says:
Simply use debugging methods and trace your VarGet/VarSet name.
Then you would see that it has invalid characters within varname.
Your varname is
"PosSize" + symbol + bar
So for example trace it
varname = "PosSize" + symbol + bar;
_TRACE( varname );
You will see that varname simply has invalid characters.
My guess is that you have symbol names of this type:
If you would not use Varget/VarSet but would use standard way of setting variables then you would not be allowed to create variables such as following ones too. Would you?
var.16-AAPL = "Hello World";
10var = "Hello World";
+1var = "Hello World";
No, as you know already varnames have to start with underscore or letter but are not allowed to start with number or other characters. Also one and only character different from A-Z, 0-9 being allowed within variable name is underscore “_”. No point sign, no plus sign, no minus sign, no slash … etc within variable name are allowed. Have you ever used plus sign within variable name? Surely not.
So proper examples for variable names are
var1 = "Hello World";
var_20= "Hello World";
_var10_AAPL = "Hello World";
So since your var names differ from those naming rules it is the reason for your error message.