Tried to Buy Some More NeuroMetrix (NURO), But It Didn't Happen

NeuroMetrix (NURO) hit an intra-day low of $2.04. Finance.Yahoo.com was showing NURO $2.12 and put in 'buy' order at $2.20. The buy never got executed an NURO ended the day (02013.04.12) at $2.36. 52-week range: $1.98 - $5.10. The 'buy' order is good-till-cancel.