IT and software development is a fickle world. You were probably quite right to focus on SAP when you did, but now the market has shifted and there is more demand for networking specialists. I'm not convinced this is an absolute and universal phenomenon (rather than a local thing) - make sure before you embark on a networking focus that the market isn't going to shift again before you've finished training. Whichever route you go down, I'm guessing you'll be investing a fair amount to transfer from a sales career.
If you find a good company to work for, they will help you learn networking now and then help you train again afterwards for something else (e.g. SAP) if they need those skills at a later date.
Alternatively, if you have your heart set on SAP and software development and you know that you will be very good at it, you could take a gamble to train yourself up and then move around where the opportunities are. Once again, the more flexible you can be with your skills, the better.