QBASIC to erase vowel from input string using FUNCTION

DECLARE FUNCTION ERA (A$)
CLS
INPUT "Enter any string";A$
PRINT "String without vowels =";ERA(A$)
END

FUNCTION ERA(A$)
FOR I = 1 TO LEN (A$)
B$ = MID$(A$,I,1)
C$ = UCASE$(B$)
IF C$ <> "A" AND C$ <> 'E" AND C$ <> "I" AND C$ <> "O" AND C$ <> "U" THEN D$ = D$ + C$
END IF
NEXT I
ERA = D$
END FUNCTION