Modelsim6.4 se Edition Error

I am getting error, while compiling the design files from .do file with ModelSim SE 6.4 in windows. Error message as follows.

# ** Error: (vcom-7) Failed to open design unit file "F:/code/aes/pack.vhd" in read mode.# No such file or directory. (errno = ENOENT)# ** Error: C:/modeltech_6.4/win32/vcom failed.

But I am able to compile the same file by direct loading. Whatever do file I using was working fine for ModelSim 5.4E.