RC-004 warning in primetime while doing check_timing

Hi,

i get the following warning when i do
'check_timing' in Primetime:

Warning: Failed to compute C-effective for the timing arc
         (slow/AOI32X1) u_flash_statemachine/U1190/A2-->Y (falling 
neg_unate)
          because the library data is inconsistent with a linear-driver
model.
          [r/f inp_slew = 3.53753/1.26782, out_cap = 0.00423815  (lib
units)] (RC-004)


I read something under solvenet, but i still don't understand the 
warning and what can i do...

Does anybody now anything about this issue?

Best Regards
Claudia