Hi, I'm trying to compile molekel 5.1.1 on RedHat Enterprise Linux 4.5 (64-bit.) I think I have all of the prerequisite packages working successfully, but I get an error when running "gmake" to build molekel: [ 54%] Building CXX object CMakeFiles/Molekel.dir/utility/OBMSMSFormat.o /usr/local/src/molekel/molekel-5.1/src/utility/OBMSMSFormat.cpp: In member function `virtual bool OBMSMSFormat::WriteMolecule(OpenBabel::OBBase*, OpenBabel::OBConversion*)': /usr/local/src/molekel/molekel-5.1/src/utility/OBMSMSFormat.cpp:111: error: `ostream' was not declared in this scope /usr/local/src/molekel/molekel-5.1/src/utility/OBMSMSFormat.cpp:111: error: `os' was not declared in this scope make[2]: *** [CMakeFiles/Molekel.dir/utility/OBMSMSFormat.o] Error 1 make[1]: *** [CMakeFiles/Molekel.dir/all] Error 2 make: *** [all] Error 2 I'm not much of a C++ programmer, so if anyone could give any suggestions about what I can do to fix this, please let me know. -Peter Ruprecht U of Colorado