用modelsim se6.5 调用quartus中的乘法器时出错，求解答

# Loading work.mult_8# ** Warning: (vsim-3009) [TSCALE] - Module 'mult_8' does not have a `timescale directive in effect, but previous modules do.# Region: /mult_8_tb/DUT# ** Error: (vsim-3033) D:/project/mult_8.v(6): Instantiation of 'alt_mult_8b8' failed. The design unit was not found.#   Region: /mult_8_tb/DUT#         Searched libraries:#             D:\project\work# Error loading design