Tekelec ( TKLC) shares plunged 22% late Wednesday after the company swung to a fiscal first-quarter loss on weaker-than-expected sales.The Morrisville, N.C., telecom switch maker had an adjusted net loss of $9.8 million, or 15 cents a share, on $107.5 million in sales for the quarter ended in March. Those numbers compare with a pro forma profit of $20.6 million, or 28 cents a share, on revenue of $139 million in the year-ago period. Analysts were looking for an adjusted net income of 14 cents a share on $145 million in sales in the latest quarter, according to Thomson First Call. "We do not believe that the first quarter results reflect a trend in our revenues, gross margins, operating income or earnings per share or are representative of the performance we expect for the second quarter or second half of 2006," CEO Frank Plastina said in a press release Wednesday. The company blamed its weak first-quarter performance on a new accounting method and weak demand for new gear. Tekelec restated its 2005 annual report and says that with the filing of its first-quarter numbers, it is now up to date on its federal filings. The company also says it expects to release its second-quarter results on time. Tekelec shares plunged $2.64 late Wednesday to $9.05.