Most IT companies are struggling to fill certain positions, but the reasons behind their recruiting challenges are nuanced, according to a new survey by Sologig.com, CareerBuilder’s job site for computer and IT professionals. Fifty-three percent of information technology firms reported open positions for which they can’t find qualified candidates. But among those concerned about a skills gap, several causes are seen as driving factors.

“At the pace certain programming and development skills evolve, there’s no silver bullet for recruiting tough-to-fill technology jobs,” said Eric Presley, chief technology officer for CareerBuilder. “Employers have to constantly evaluate their talent needs through workforce planning and ensure their compensation is competitive enough to attract top talent. IT workers, meanwhile, must always be polishing their existing competencies and acquiring new ones to stay relevant.”

The survey asked IT employers, “What is causing the skills gap?” Answers included:

• Gaps in expectations around wages: 40 percent
• New and shifting technologies: 39 percent
• Job requirements that are above entry-level: 38 percent
• Education gaps in particular areas: 33 percent
• Gaps in on the job training: 33 percent
• Job requirements that are too specific: 29 percent
• Outsourcing of jobs to other countries: 26 percent

Harris Poll conducted the online survey within the U.S on behalf of CareerBuilder among 240 information technology employers between Oct. 17 and Nov. 6, 2013.