How to make Valgrind debugger step through a program

Good morning, I am trying to use the Valgrind debugger to step through a program.

My valgrind command line is valgrind -tool memcheck --leak-check=full --db-enable=yes ./MatchUpAcurate.exe.

I am using valgrind-3.5.0 on Centos Linux release 5.5 with gdb version 7,0.1-23.el5_5.2.

I enter Yes when valgrind asks the question Attach to Debugger. Then, the valgrind debugger returns with: 4428: return new tuple2(2, i++, p->next());

When I try to use the gdb step or continue command, valgrind says

[New Thread 0x410fd10 (LWP 6548] Cannot find user-level thread for LWP 6551: generic error.

When I try to use valgrind --single-step=yes debugger option on the valgrind command-line, valgriind says Bad option aborting.

Could any valgrind users show me how to step through C++ source code or continue through a program? Thank you.