Cyclone III configuration with EPCS4 issues

Hi all,

I need your help concerning an issue of serial flash configuration .
I have cyclone III FPGA (EPC3C16) connected on a board with the serial flash EPCS4.
I have only one header(JTAG) , so in order to flash the serial flash I use the SFL.
When I program the FPGA directly with the USBblaster it works perfectly.
But when I generate .jic from .sof and want to configure the flash through the SFL, Quartus notifies that verification and blank check are failing for device .
In addition to this the FPGA doesn't boot from flash.
The signals CON_DONE, nSTATUS and nCONFIG are all released high after configuration.
In the beginning I was suspecting connection between flash and FPGA.So I wrote a VHDL driver in order to access directly to the Flash (Read,write byte, read silicon ID...).
The Flash is behaving well!
I am now confused and I don't know what can be really the problem?
Please if you have some advice I will be very gratefull

Best Regards
Nrd