Modelsim only does what you ask, so you need to look at what you are asking it to do :)
For example, how are you getting Modelsim to attempt to compile this file? Are you asking Quartus to run an RTL simulation, or are you running a Tcl script?
Chances are you have an invalid filename that you are trying to pass to vcom, eg.,
vcom c:/vhdl/my_vhdl_file.vhd
would work, but
vcom
c:\vhdl\my_vhdl_file.vhd would not, since the backslash is a Tcl escape character, but ...
vcom {
c:\vhdl\my_vhdl_file.vhd} will work, since it passes the path without interpreting the contents of {}
You might also look for spaces in your paths ... they can be used, but you have to use "" or {} to pass the path as a "single string", since that is what Tcl wants to see.
Cheers,
Dave
