Fan speed to the max after superdrive replacement with SSD

I tried to install a second SSD drive in my iMac 27" (mid 2011). I followed the guide to install it to the free SATA port only to find out that I was missing the connecting cable. So I assembled back to the part that I had to place the superdrive and I used a caddy (which I already had) following the instructions here.

I closed the computer and installed Mavericks and found out that the fan was working at full speed.

I did transfer the thermal sensor from the superdrive to the caddy. Does anyone know what could be wrong?

I when through all the cables to check if anyone was not correctly in place and still have the fan at full speed,

Other than that the iMac is working extremely fast and without any other problem.