Which memory for a 164LX motherboard?

[Axianet.ch - Steven Moix]

So, my second post today but I learn more on this list than ever :)

At home I have a 164LX motherboard with a 533MHz CPU but I didn't manage
to make it boot, it makes 5 beeps (manual indicates that the RAM is not
detected). So my question is, which RAM do I EXACTLY need to run on this
mobo?

In the presentation manual
(ftp://ftp.digital.com/pub/Digital/info/semiconductor/literature/164lxmpb.pdf)
there is only written:

Synchronous DRAM (SDRAM) memory subsystem includes:
–32MB to 512MB memory
–Two banks of 128-bit memory
–168-pin unbuffered SDRAM DIMMs

For me that means normal DIMM sticks by pair (non ECC, non registred and
maximum 128Mo) but it didn't work here. I tried with:
2 128Mo PC133 Kingston sticks
2 128Mo PC133 NoName sticks
2 256Mo PC133 Apacer ECC Registred sticks

All with no luck...Is my board dead or am I wrong somewhere?

Thanks
Steven