ERROR: clSetKernelArg(): CL_INVALID_MEM_OBJECT

Hey there. Complete newbie to hashcat here, although I have some experience using the command line. I'm running Windows 7 64-bit, and I'm trying to use hashcat to get a plaintext password from a single MD5 hash. After downloading the latest version of the program and unzipping it, I CDed into the hashcat directory, created a hashes.txt file containing the hash I want to crack,  as well as a results file called results.txt. I've spent a fair bit of time looking at the documentation and figuring out what I can from it, and the best attempt at the syntax that I've managed to get so far was the following:


I understand it's probably wrong or grossly impractical. Anyway, running that command, I get the following error:


I tried Googling, but that didn't help, hence why I'm here. I'd really, really appreciate some guidance at this point, namely in regards to what the error means.

Thanks!