singularity issue in mlogit model when model contains interaction

I'm using below r command on my choice model data which is perfectly working:

• mlmodel_BL <- mlogit(choice ~ Price + Feature + Brloy , data = mldata_BL, reflevel = "Brand4")

but when I want to add interaction there, I face singularity error.

• mlmodel_BL2 <- mlogit(choice ~ Price + Feature + Brloy + Income*Price , data = mldata_BL, reflevel = "Brand4")

error:

• Error in solve.default(H, g[!fixed]) :
• Lapack routine dgesv: system is exactly singular: U[7,7] = 0

I tried below command and it worked, however, I prefer to include interaction form in my model instead of changing my data:

• mldata_BL$Price_Income <- mldata_BL$Price * mldata_BL$Income

• mlmodel_BL2 <- mlogit(choice ~ Price + Feature + Brloy + Price_Income , data = mldata_BL, reflevel = "Brand4")

would you please guide me on what might cause this issue in my code? thanks