I'm in a lot of trouble.

I would like to analyze the thermal conduction from the LED light source to the heat sink, but the results are obviously wrong.

Please let me know why the temperature is negative and whether the setting is strange．

The heatsink is made of aluminum（5454-H111).

The LED is made of ceramics.

The base material is copper.

Ambient temperature is 300K.

Convection is 3W/(m^2·k).