Sluggish acceleration after rebuilding the transmission

I recently rebuilt the automatic transmission. I am just a novice but I believe I did everything correctly. Installed transmission and it was very sluggish at take off. Also the cog transmission light came on the instrument panel. I heard that it went into a safety limp mode and the computer needed to be reset. I purchased an inexpensive scanner tool but when I tried it on the transmission said unable to communicate. It did however seem to communicate to the engine. I called a transmission guy who I know he confirmed it needed to be reset. I brought it to him his computer was also unable to communicate with it. I wiggled wires by computer nothing. Checked fuses, wires that were connected to transmission. Checked transmission fluid level. I am pretty sure it is something connected to me working on the transmission.