Missing argument size variable

An ARG or LOCAL directive does not have a symbol name following the
optional = at the end of the statement. For example,

   ARG   A:WORD,B:DWORD=   ;error, no name after = 
   LOCAL X:TBYTE=          ;same error here 

ARG and LOCAL must always have a symbol name if you have used the optional
equal sign (=) to indicate that you want to define a size variable.