Aberdeen manager Jimmy Calderwood admits he has been frustrated by his side's up and down form this season.Calderwood believes beating Celtic in the Scottish Cup quarter-finals would simply add to the unpredictability of his side's erratic campaign to date.

Highs such as drawing with Bayern Munich in the UEFA Cup have been punctured by polarising lows, including the comprehensive CIS Insurance Cup semi-final defeat by Dundee United.

Aberdeen's Scottish Premier League campaign has certainly suffered from inconsistent form, leaving the Dons eighth in the standings - a far cry from last season's third-placed finish.

The Pittodrie club's showings in the top flight have generally been good since Calderwood took charge in 2004, despite losing players such as Kevin McNaughton and Russell Anderson over the years.

The Aberdeen boss has not enjoyed as much success in the cups - although his fortunes in knockout competitions have improved this term, even if Calderwood believes progress in the Scottish Cup would sum up a bizarre season.

He said: "We got to the semi-final of the CIS Cup this year and we are in the quarter-finals of the other one.

"You have no divine right to get to finals every year, although some people think you have and it's a very difficult thing to do.

"This season has been really topsy-turvy and if we did win the game it would probably just add to the inconsistency of it.

"We have done great in the league for the most part, although this season we have been poor.

"But it's difficult when a lot of your best players go away to keep it going and keep the quality up."

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