Im trying to set one variable equal to another but it says "No default member found for type 'Decimal'" what does that mean?

Both the varuables are deciamls, one is a regular decimal that I declare in the sub and another is an array that I declare in the class. The line is:
tempx = xo(i)
this is in a for loop with i as the variable.

I feel really stupid now. I had the wrong variable it should have been xo(i) not x(i). I knew that I had it declared right i just put the wrong variable down. Thanks anyway.