The Normalized Lagrange Multiplier (NLM) method was shown to be useful in network parameter error detection, but suffered from occasional failure in certain cases. This paper exploits the advantages of PMUs and proposes a solution to the detection failure issue. The relationship between NLMs and parameter errors is first derived then used to identify insensitive NLMs which account for the issue of missing parameter error. Subsequently, a PMU placement strategy is proposed to improve the performance of the NLM method. Simulation results in the IEEE 14-bus test system show that the increased redundancy and accuracy gained by the incorporation of PMUs significantly facilitate the detection of parameter errors which was not possible by using only SCADA measurements.