There is a list of control change numbers in the I/O menu, CTRL page, the button is on the front panel of the axe. Find the number for Tap. I highly suggest leaving the numbers on the axe at default. Change the CC# of the switch on your voodoo lab pro to that number.
Once the switch works, you have to make sure the Tempo parameter in the delay block is set to anything other than "None." 1/4 note is the usual setting for having the tap tempo control the delay tempo. With a setting of None, you set the delay time so a specific time setting.