Charleston-based software maker Blackbaud Inc. reported a 21 percent increase in first-quarter profit Thursday while slightly lowering its sales expectations for 2008.

Blackbaud's earnings for the three months ended March 31 increased to $7 million, or 16 cents a share, compared with $5.8 million, or 13 cents per share, in the same period a year earlier. Revenue for the quarter jumped 26 percent to $69 million.

Chief Executive Marc Chardon said the results were in "the upper half" of the Daniel Island company's expectations. "We are pleased with this growth and overall financial performance considering the challenging macro-economic environment in which we are currently operating," he said.

Wall Street expected better. Eight Blackbaud analysts surveyed by Thompson Financial Network had expected the firm to post a profit of 20 cents a share. Shares of Blackbaud fell 3.5 percent to $22.96 Wednesday in trading on Nasdaq. The technology company, which sells financial software and services to nonprofit fund-raising organizations, now boasts more than 19,000 customers and about 1,500 employees. In the first quarter it had relatively good results with its NetCommunity product, which helps groups raise funds over the Internet, rather than Blackbaud's traditional database products.

Blackbaud also did well outside of the U.S., posting a 30 percent increase in international revenue. Chardon said the company hopes to eventually garner one-third of its sales from other countries. Still, Blackbaud garnered most of its growth in the quarter from subscription fees from incumbent customers, as opposed to groups purchasing its products for the first time. While sales to colleges and universities have been "resilient," nonprofits that focus on the arts have grown more cautious in the listless economy.

Blackbaud lowered the high end of its full-year sales expectations to $301 million, from $305 million. It still expects to post an annual profit of between $72 million and $74 million, which would be an increase of 15 percent to 18 percent.

"I don't see gloom and doom," Chardon said. "I feel quite comfortable that we have a lot of opportunity in front of us."