The auditor checks the company's financial statements using sampling. There are 100 sales transactions made by the company. Of the 100 transactions, materiality is set at 5% or 5 transactions. The auditor took a sample of 40 transactions, and it turns out that of the 40 transactions examined, there were no deviations found. Based on the results of the sampling inspection, the auditor concluded that there was no material misstatement. When in fact, of the 100 transactions there were 10 transactions that occurred irregularities or errors, it's just a coincidence that the ten transactions were not taken in the sample.

What we called the risk involved in this case example? Explain your answer!