hallo, i have a problem, the followed program gives back an error, error:: Undeclared(first use in function), why this error appears all tokens are declared, but this error comes, can anyone help me, here are the lex and yac files.thanks

lex:

%{
int yylinenu= 1;
int yycolno= 1;
%}

%x STR
DIGIT                     [0-9]
ALPHA                     [a-zA-Z]
ID                        {ALPHA}(_?({ALPHA}|{DIGIT}))*_?
GROUPED_NUMBER        ({DIGIT}{1,3})(.{DIGIT}{3})*
SIMPLE_NUMBER             {DIGIT}+
NUMMER                {GROUPED_NUMBER}|{SIMPLE_NUMBER}
%%
<INITIAL>{
[
]                      {++yylinenu ; yycolno=1;} 
[ ]+                      {yycolno=yycolno+yyleng;} 
[	]+             {yycolno=yycolno+(yyleng*8);} 
"*"                       {return MAL;}
"+"                       {return PLUS;}
"-"                       {return MINUS;}
"/"                       {return SLASH;}
"("                       {return LINKEKLAMMER;}
")"                       {return RECHTEKLAMMER;}
"{"                       {return LINKEGESCHWEIFTEKLAMMER;}
"}"                       {return RECHTEGESCHEIFTEKLAMMER;}
"="                       {return GLEICH;}
"=="                      {return GLEICHVERGLEICH;}
"!="                      {return UNGLEICH;}
"<"                       {return KLEINER;}
">"                       {return GROSSER;}
"<="                      {return KLEINERGLEICH;}
">="                      {return GROSSERGLEICH;}
"while"                   {return WHILE;}
"if"                      {return IF;}
"else"                    {return ELSE;}
"printf"                  {return PRINTF;}
";"                       {return SEMIKOLON;}  
//[^
]*                { ;}
{NUMMER}                  {return NUMBER;}
{ID}                      {return IDENTIFIER;}
"                {BEGIN(STR);}                  
.                         {;} 
}

<STR>{ 

                        {++yylinenu ;yycolno=1;} 
([^"\]|"\t"|"\n"|"\r"|"\b"|"\"")+        {return STRING;}
"                                             {BEGIN(INITIAL);}
}
%%
yywrap()
{
}

YACC:

%{
#include stdio.h>
#include string.h>
#include "lex.yy.c"

void yyerror(char *err);
int error=0,linecnt=1;
%}

%token IDENTIFIER NUMBER STRING COMMENT PLUS MINUS MAL SLASH LINKEKLAMMER RECHTEKLAMMER LINKEGESCHWEIFTEKLAMMER RECHTEGESCHEIFTEKLAMMER GLEICH GLEICHVERGLEICH UNGLEICH GROSSER KLEINER GROSSERGLEICH KLEINERGLEICH IF ELSE WHILE PRINTF SEMIKOLON


%start Stmts

%%
Stmts : Stmt
{puts("		Stmts : Stmt");}
|Stmt Stmts
{puts("		Stmts : Stmt Stmts");}
; //NEUE REGEL----------------------------------------------
Stmt : LINKEGESCHWEIFTEKLAMMER Stmts RECHTEGESCHEIFTEKLAMMER
{puts("		Stmt :  {  Stmts  } ");}
|IF LINKEKLAMMER Cond RECHTEKLAMMER Stmt
{puts("		Stmt :  (  Cond  )  Stmt");}
|IF LINKEKLAMMER Cond RECHTEKLAMMER Stmt  ELSE Stmt
{puts("		Stmt :  (  Cond  )  Stmt  ELSE  Stmt");}
|WHILE LINKEKLAMMER Cond RECHTEKLAMMER Stmt
{puts("		Stmt :  PRINTF  Expr  ; ");}
|PRINTF Expr SEMIKOLON
{puts("		Stmt :  PRINTF  Expr  ; ");}
|IDENTIFIER GLEICH Expr SEMIKOLON
{puts("		Stmt :  IDENTIFIER   =  Expr  ; ");}
|SEMIKOLON
{puts("		Stmt :  ; ");}
;//NEUE REGEL ---------------------------------------------
Cond: Expr GLEICHVERGLEICH Expr 
{puts("		Cond :  ==  Expr");}
|Expr UNGLEICH Expr
{puts("		Cond :  !=  Expr");}
|Expr KLEINER Expr
{puts("		Cond :  <  Expr");}
|Expr KLEINERGLEICH Expr
{puts("		Cond :  <=  Expr");}
|Expr GROSSER Expr
{puts("		Cond :  >  Expr");}
|Expr GROSSERGLEICH Expr
{puts("		Cond :  >=  Expr");}
;//NEUE REGEL --------------------------------------------
Expr:Term 
{puts("		Expr : Term");}
|Term PLUS Expr 
{puts("		Expr : Term  +  Expr");}
|Term MINUS Expr 
{puts("		Expr : Term  -  Expr");}
;//NEUE REGEL --------------------------------------------
Term:Factor
{puts("		Term : Factor");}
|Factor MAL Term
{puts("		Term : Factor  *  Term");}
|Factor SLASH Term
{puts("		Term : Factor  /  Term");}
;//NEUE REGEL --------------------------------------------
Factor:SimpleExpr
{puts("		Factor : SimpleExpr");}
|MINUS SimpleExpr
{puts("		Factor :  -  SimpleExpr");}
;//NEUE REGEL --------------------------------------------
SimpleExpr:LINKEKLAMMER Expr RECHTEKLAMMER
{puts("		SimpleExpr :  (  Expr  ) ");}
|IDENTIFIER
{puts("		SimpleExpr :  IDENTIFIER ");}
|NUMBER 
{puts("		SimpleExpr :  NUMBER ");}
|STRING
{puts("		SimpleExpr :  String ");}
;//ENDE -------------------------------------------------
%%
void yyerror(char *msg)
{
 error=1;
 printf("Line: %d , Column: %d : %s 
", yylinenu, yycolno,yytext, msg); 
}
int main(int argc, char *argv[])
{

        int val;
        while(yylex())  
        {       
         printf("
",yytext);       
    }
    return yyparse();
}