I use an I2C EEPROM (Atmel AT24C256). I can read data, but if I try to write something, I don't get an acknowledge after the first byte.

I send 10100001 as first byte for reading - everything is allright.
I send 10100000 as first byte for writing - acknowledge doesn't go low.

Thanks for any suggestions,
Jörg

PS: I'm new to I2C, but I use the same send- and receive-routines for read and write. So I don't think that the code is wrong.