LTSP error loading boot image

We r trying 2 configure LTSP 3.1 on our linux server having following
> specifications:
> Pentium 4 – 1.8 Ghz
> 256 MB RDRAM
> 3COM’s 3C905C-TX-M for connecting thin client
> Intel’s 82801DB PRC for reaching LAN and Internet.
> OS is Linux Fedora Core 3.

Thin Client specs:
> STPC Processor 50 MHz
> 64Mbits SRAM
> Digital Tulip ADMtek Comet
>
> We had already installed the base 4 packages core,kernel,xcore and
> xfonts and also ltscfg.
> DHCP is running and thinclient is getting IP address from server.
> TFTPD is also runnig but client is not able to download the kernel image.
only dots(.) start appearing and process goes on.
what should we do now?