PHP Post-Method prepare() returns False - php

Question

Here is the Problem, I want to create a Post-Method for my Webservice. I'm uing the Slim Framework with PHP7 and an SQLite3 Database. I have the following code implemented:
$app->post('/api/generalinformation', function ($request) {
try {
$db = new PDO("sqlite:D:/Schule/notfunk_app/IPNF.db") or die("Cannot open Database");
$query = "insert into nlv_GeneralInformation (SystemID, InformationID, Title, Description, Importance) values (:SystemID, :InformationID, :Title, :Description, :Importance);";
$stmt = $db->prepare($query);
if($stmt === false){
die("prepare() failed");
}
$SystemID = $request->getparsedBody()["SystemID"];
$InformationID = $request->getparsedBody()["InformationID"];
$Title = $request->getparsedBody()["Title"];
$Description = $request->getparsedBody()["Description"];
$Importance = $request->getparsedBody()["Importance"];
$stmt->bindParam(":SystemID", $SystemID, PDO::PARAM_INT);
$stmt->bindParam(":InformationID", $InformationID, PDO::PARAM_INT);
$stmt->bindParam(":Title", $Title, PDO::PARAM_STR);
$stmt->bindParam(":Description", $Description, PDO::PARAM_STR);
$stmt->bindParam(":Importance", $Importance, PDO::PARAM_INT);
$stmt->execute();
$db = null;
} catch (PDOException $e) {
echo $e->getMessage();
}
});
But the prepare() funktion always returns me false. I've testet the query and it works.