BaseX XQJ API error on undefined variable, while variable is defined

[hugs]

I'm using BaseX XQJ API to execute xquery queries on XML files within my java application. The following xquery that I constructed nicely generates the output that I want:\[code\]let $doc := doc("eprints")for $i in distinct-values($doc//issn)let $jn := $doc//paper[issn = $i]/publicationwhere (count(distinct-values($jn)) > 1)return <issn num="{$i}">"{$jn}"</issn>\[/code\]After convincing myself that this query works by testing it in the BaseX application, I implemented this query in java code.\[code\]public static void main(String[] args) throws XQException{ XQDataSource ds = new BaseXXQDataSource(); ds.setProperty("serverName", "localhost"); ds.setProperty("port", "1984"); ds.setProperty("user", "xxxx"); ds.setProperty("password", "xxxxx"); ds.setProperty("databaseName", "eprints"); XQConnection conn = ds.getConnection("admin", "admin"); XQExpression xqe = conn.createExpression(); XQResultSequence result = xqe.executeQuery("let $doc := doc(\"eprints\")"+ "for $i in distinct-values($doc//issn)"+ "let $jn := $doc//paper[issn = $i]/publication"+ "where (count(distinct-values($jn)) > 1)"+ "return <issn num='{$i}'>'{jn}'</issn>" ); }\[/code\]This code however resulted in a error stating that the $jn variable could not be found:Exception in thread "main" javax.xml.xquery.XQQueryException: [XPST0008]: Undefined variable $jn. When looking at the query one can see that $jn actually is defined in the let-statement within the for-statement. However, when I directly insert the expression assigned to $jn where $jn was used, the code does work correctly:\[code\]public static void main(String[] args) throws XQException{ XQDataSource ds = new BaseXXQDataSource(); ds.setProperty("serverName", "localhost"); ds.setProperty("port", "1984"); ds.setProperty("user", "admin"); ds.setProperty("password", "admin"); ds.setProperty("databaseName", "eprints"); XQConnection conn = ds.getConnection("admin", "admin"); XQExpression xqe = conn.createExpression(); XQResultSequence result = xqe.executeQuery("let $doc := doc(\"eprints\")"+ "for $i in distinct-values($doc//issn)"+ "where (count(distinct-values($doc//paper[issn = $i]/publication)) > 1)"+ "return <issn num='{$i}'>'{$doc//paper[issn = $i]/publication}'</issn>" ); }\[/code\]It seems like the BaseX XQJ API is unable to handle queries which have a let-statement within a for-statement. Does anyone know what the cause of the error is?