The Disability Discrimination Act Part 2 and also the Disability Equality Duty (2005) places a legal duty on organisations to ensure that their recruitment and selection processes are not discriminating against disabled people.
Many disabled people do not see organisations positively promoting disability equality and as a consequence are more likely to seek jobs elsewhere. There are a number of ways to promote your organisations' commitment to disability equality.
Another explanation may be the fact that you are not using data management to review and evaluate your recruitment processes and performance.