Blur Group's shares plunged after warning that revenue from some projects in 2013 would not be recognised until 2014 and 'beyond'.Revenue will, therefore, be lower than previously expected for the 2013 financial year, the tech group said in a trading update on Thursday.The company predicts revenue between $5.3m to $5.6m, compared to $2.8m in 2012, with total project bookings for the same period of $22.2m, up from $2.4m the prior year. The firm said longer time-frame projects have started to be managed through the Exchange, which has resulted in extended periods between submission, kick-off and completion. "Due to these longer timeframes, the board has taken a more conservative view of project revenue recognition with several larger value projects extending over several reporting periods or years and therefore a significant proportion of the revenue associated with project bookings achieved in 2013 will be recognised in 2014 and beyond," the company said in a full-year 2013 trading update on Thursday. Shares tumbled 33.70% to 300p at 11:19.RD