Work Experience

I have been working with 6 employers in the past 2 years. My work is a contract bases for 6 months to 1 years bases. Now, I am planning to switch to permanent job, but in the interview, people are not considering my work experience because of short contract periods with the employers. But I have worked in realy very tough and challenging projects, and I have obtained certifications in languages, my work experience suits the current vacancy I have applied eventhough interviewer does’nt consider my application. How to handle such situation?