XDM and X not beggining

[Paulo Henrique Baptista de Oliveira]

        Hi all debian sparc users,
        I upgrade my Sparc 4 to potato and now cant begin X:
        The error when I try to start xdm  is:
        PEXExtensionInit: Couldn't open default PEX font file  Roman_M
        Could not open default font fixed
        And I have xfonts-base 100dpi, 75dpi installed...
        What I can do?
        Thanks a lot,
        Paulo Henrique