Use dd to write data starting from a specific location

I want to use dd to write data starting from a specific location (basically skip the first 50000 bytes ) on a disk and start writing after the first 50000 bytes. I tried doing this

dd of=/dev/disk1 if=/dev/random seek=50000

I let the above line run for few mins and then when I cancel it out, I get this

0+6 records in
0+0 records out
0 bytes (0 B) copied, 79.2458 s, 0.0 kB/s

Looks to me nothing got copied. Am I doing anything wrong ?