Joined primary key does not work as intended

[NiklasAurora]

With the following tables, I can not use the $tableIdColumn (#6). I am not allowed to save and instead it goes directly to update, as it can not find a joined primary key. However, as there is no row to update, nothing happens. If I remove the $tableIdColumn, I can save but I would not be able to update the OrderItem.

CREATE TABLE IF NOT EXISTS Product (
    `productID` INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL,
    `productManufacturer` VARCHAR(80) NOT NULL,
    `productName` VARCHAR(80) NOT NULL,
    `productOriginCountry` VARCHAR(40) NOT NULL,
    `productWeight` INTEGER NOT NULL,
    `productSize` VARCHAR(3) NOT NULL,
    `productSellPrize` INTEGER NOT NULL,
    `productBuyPrize` INTEGER NOT NULL,
    `productColor` VARCHAR(20) NOT NULL,
    `productAmount` INTEGER,
    `productCategoryID` INTEGER,
     FOREIGN KEY (`productCategoryID`) REFERENCES Category(`categoryID`)
) ENGINE INNODB CHARACTER SET utf8 COLLATE utf8_swedish_ci;

CREATE TABLE IF NOT EXISTS Orders (
    `orderID` INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL,
    `userID` INTEGER NOT NULL,
    `purchaseTime` DATETIME DEFAULT CURRENT_TIMESTAMP,
    `sentTime` DATETIME NULL,
    `couponID` INTEGER,
    `orderStatus` VARCHAR(40),
     FOREIGN KEY (`userID`) REFERENCES User(`userID`),
     FOREIGN KEY (`couponID`) REFERENCES Coupon(`couponID`)
) ENGINE INNODB CHARACTER SET utf8 COLLATE utf8_swedish_ci;

CREATE TABLE IF NOT EXISTS OrderItem (
    `orderID` INTEGER NOT NULL,
    `productID` INTEGER NOT NULL,
    `productAmount` INTEGER NOT NULL,
     PRIMARY KEY (`orderID`, `productID`),
     FOREIGN KEY (`orderID`) REFERENCES Orders(`orderID`),
     FOREIGN KEY (`productID`) REFERENCES Product(`productID`)
) ENGINE INNODB CHARACTER SET utf8 COLLATE utf8_swedish_ci;

PHP 7.1.7
MySQL Ver 14.14 Distrib 5.7.21
anax/database v1.1.9

[mosbth]

I checked it up and it should be a possibility to use a primary key that is combined from several fields. But, I need to investigate.