Syntax issue for multiples of a character

[The-Mad-Duck]

I was writing a line as below:
\'{SCHAR}{2,}\' { fprintf(stderr, "character constant %s too long on line %d\n", yytext, no_of_lines); }
And noticed an error was highlighted over {2,}. However, this is a valid line meaning "2 or more of". In this case, the whole line means:
(quote) 2 or more of SCHAR (quote)

This compiles fine when using a flex compiler on Unix and is listed as correct in the flex manual.