Figuring out how to power a solenoid
You have not posted a schematic for your question so we can only give general advice on debugging your circuit. 







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. You should have wired the circuit up something similar to this.



Figure 2. You need to troubleshoot in a fashion similar to this.

Add a schematic to your question, do some basic troubleshooting and then modify your post to give the results of your investigation. Post a comment here to alert me to the update.









simulate this circuit

Figure 2. Where to take voltage readings.

If possible, create a program to turn the solenoid off and on every few seconds. Connect your multimeter on DC volts to 'B' and you should see the the voltage switch between 3.3 V and 0 V. Trace through the other points and record the values. Report back.