Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| District | Vacator | Reason for change | Successor | Date successor seated |
| --- | --- | --- | --- | --- |
| Kentucky 7th | George Robertson (DR) | resigned before Congress met | John S. Smith (DR) | Seated December 3, 1821 |
| Kentucky 8th | Wingfield Bullock (DR) | Died October 13, 1821, before Congress met | James D. Breckinridge (DR) | Seated January 2, 1822 |
| Maryland 6th | Jeremiah Cosden (DR) | Cosden's election was contested by Reed | Philip Reed (DR) | Seated March 19, 1822 |
| Pennsylvania 14th | Henry Baldwin (DR) | Resigned on May 8, 1822 | Walter Forward (DR) | Seated December 2, 1822 |
| South Carolina 9th | James Blair (DR) | Resigned on May 8, 1822 | John Carter (DR) | Seated December 11, 1822 |
| South Carolina 2nd | William Lowndes (DR) | Resigned on May 8, 1822 | James Hamilton, Jr. (DR) | Seated January 6, 1823 |
| Pennsylvania 6th | Samuel Moore (DR) | Resigned on May 20, 1822 | Samuel D. Ingham (DR) | Seated December 2, 1822 |
| South Carolina 4th | James Overstreet (DR) | Died May 24, 1822 | Andrew R. Govan (DR) | Seated December 4, 1822 |
| Virginia 2nd | Thomas Van Swearingen (F) | Died on August 19, 1822 | James Stephenson (F) | Seated December 2, 1822 |
| Florida Territory At-large | Vacant | Florida Territory was organized on March 30, 1822 | Joseph M. Hernández | Seated January 3, 1823 |
Question:
What is the reason for change when maryland 6th is the district? 
Answer:
Cosden's election was contested by Reed