This is a very Simple way to modification the Standart USB converter to OTG USB.
Most Mini or Micro USB to USB converters are not working if you want to use it for the OTG converter, because the 4. pin of the micro USB plug is not connected.
This below is an original cable schematic :
If you want to use it for working OTG adapter you have to connect the micro USB connector 4. pin to GND (5. pin).
Like this below :
This schematic is working for me. Let to try this stuff.
Original document USB OTG mechanical