Error: ORA-02270 | Help Needed

I'm having a headache over this error:
SQL Error: ORA-02270: no matching unique or primary key for this column-list
02270. 00000 - "no matching unique or primary key for this column-list"

Someone save me from this agony and tell me what's wrong with my code.

Code:

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CREATE TABLE Concert
(  CDate          DATE NOT NULL,
    StartTime      TIMESTAMP NOT NULL,
    VHall          VARCHAR2(20) NOT NULL,
    FinnishTime    TIMESTAMP NOT NULL,
    OName          VARCHAR2(15) NOT NULL,
    OFee          DECIMAL(19,4) NOT NULL,
    PRIMARY KEY (CDate, StartTime, VHall),
    FOREIGN KEY (VHall) REFERENCES Venue(VHall),
    FOREIGN KEY (OName) REFERENCES Orchestra(OName) ) ;

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Code:

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CREATE TABLE ConcertStandin
(  CDate          DATE NOT NULL,
    StartTime      TIMESTAMP NOT NULL,
    VHall          VARCHAR2(20) NOT NULL,
    MNo            VARCHAR2(15) NOT NULL,
    StandinFee    DECIMAL(19,4) NOT NULL,
    PRIMARY KEY (CDate, StartTime, VHall, MNo),
    FOREIGN KEY (CDate) REFERENCES Concert(CDate),
    FOREIGN KEY (StartTime) REFERENCES Concert(StartTime),
    FOREIGN KEY (VHall) REFERENCES Venue(VHall),
    FOREIGN KEY (MNo) REFERENCES Musician(MNo) ) ;

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Thanks in advance.

When you create a foreign key the table/column you reference must be either primary key or unique key.