As i understand its specs it's due to the concept of the SP-2: The SP-2 does not have a switch output like the SP-1, instead it has two pedal outputs. So when switching you do not switch as necessary for the Profiler but only choose the second Expression Pedal output of your SP-2. By switching twice you seem to trigger the assigned slot as you would with a latching switch. The Profiler expects an unlatched switch. I'd check the SP-2 manual for details.
The LF only accepts momentary switches, what you need is a true on/off latching switch. You can replace the toe switch pretty easily and put in one that will do what you want. Most electronic stores will carry those switches, and then it's resolver three wires.
Sean
I wanted the same thing as I noticed that when I increased the Gain I got lost in the mix on certain amp profiles. I set up a Pure Booster in slot D to roll the Gain up before the Preamp section and also set up a Confidence Booster in slot X which being after the Preamp really just increases Volume for the most part, both were assigned to and work off of the same pedal, I leave both slots, D and X, on with the pedal backed off normally and just step down on the pedal when I wanted more gain/boost. I use a Roland FC300 but I'm sure this will work with any midi expression pedal.
Forget my comments about a latching switch for the kemper, it needs the momentary switches. Thanks Hell-G
If you think you have a bad switch they are easy to check if you have a simple continuity checker or volt meter. Want to measure resistance across the tip/ring of the cable plugged into the footswitch for output 2 on the mission pedal. You should see the meter go from open to closed with the button press then back to open when you release the button.
Sean
Is there another way to control pre and post volume in the same time? I want to control gain and volume with the expression pedal, maybe a latch switch could do the trick? I don't really need it to be progressive but very easy to switch from low gain with less volume to high gain with more volume. I don't want to tap danse because I have to change from one to the other quickly and often.
The only way to actually control them at the same time, within the pedal, would be if you had a double pot - two sets of contacts, so both output jacks are being controlled at the same time without being shorted together. I think wah/expression pedals just use a regular pot with a gear fitted on instead of a knob - if that's the case, you might be able to buy a 10k linear double pot and swap it out. Otherwise, Mission's Pigtronix is exactly what you're looking for if you have the cash.
For the same thing within the Kemper, the only solution I can think of would be to set your pedal up to control Wah and then have a pair of Wah Pedal Booster effects, one before the amp and one after. That's eating up two slots and preventing you from using the wah, though.
However, your SP1-LF should work fine for switching a boost effect on and off, but I can't find the page in the manual that tells you how to set up switches.
Hey thanks for all of your suggestions guys!!! I choose to go with Lokassena idea to use two wah boosters (one in pre and one in post) it works exactly how it should for what I wanted with just one expression pedal! You made my day man! 
Ha! Yes thanks Lokassena for telling him the same thing I tried to tell him the day before, lol. Just a little light humor 
so long as you got the help I'm happy!! Remember you can also adjust the pedal range in the booster at slot X. This will allow you to dial in actual volume change to taste as you roll in the gain. I keep mine pretty minimal, just enough so I'm not getting lost in the mix with more gain. Peace!
Ha! Yes thanks Lokassena for telling him the same thing I tried to tell him the day before, lol. Just a little light humor
Hi Booyah! And thanks for your help! I think that your idea was excellent but my problem was that I needed to use one expression pedal connect to the KPA pedal 1 and control two boosters (pre and post) in the same time. The only way to achieve this, at my knowledge, is using two "wah booster" (as suggested by Lokasenna) because when you set the pedal 1 as "expression/wah" you control all wah instances in the chain in the same time.
Yup that's how I have them set up. I have,a booster in slot D and another in slot X controlled simultaneously by my Wah pedal, only have the booster in slot X to increase the volume a bit. I noticed, especially on Mesa Boogie profiles, that when the gain goes up the tone get mushy and loses presence (?), so I add a tad more volume to it. Enjoy your Kemper, I sure do.
