No, you are eligible to appear for CDS examination conducted by UPSC. CDS stands for Combined Defence Service.

The examination is conducted in two stages as Written and Interview and it is necessary to qualify in both stages for final selection. The eligibility to appear for examination for recruitment in Indian Army is :-

Candidate must have passed graduation from any recognised university.

Candidate's age must be between 19-24 years.

Only unmarried candidates are eligible to appear for examination.

So, you are eligible to appear for examination, if you have all the above qualification to appear for examination. For more information about examination visit at http://www.upsc.gov.in.