Help needed with spi interfacing to mcp3208 and ads7871

Hello,
so far i succeeded to interface the minicore 6750 (and the rcm4000) with max4820, max31865 (an RTD-to-Digital Converter) and a touchscreen display but i have serious problems with ads7871 and mcp3208
I dont know what's the problem, the spi's signals (cs, miso, mosi and the serial clock) are connected to a logic analyzer,
and the communication (cs, clock and the mosi from the minicore) seems ok, but i'm not receiving the chips replies!!(and i'm going MAD!!)
I use the same spi with other chips, and i changed the cs only to connect these chips
Maybe it's the schematics...there is someone who succeeded to interface with the ads787x or mcp320x chips family and is so kind to share the schematics?
Thanks in advance