[amibroker] StaticVarGet & Type Mismatch

[spi_maker]

For these statements

  StaticVarSet("Trade_Amount", 10000);
  Available_Cash = ibc.GetAccountValue("CashBalance")
  if(StaticVarGet("Trade_Amount") > Available_Cash)
    {
      StaticVarSet("Trade_Amount", Available_Cash);
    }
  _TRACE("Trade_Amount " + StaticVarGet("Trade_Amount") + " Available_Cash " + 
Available_Cash);

Trace Results
Trade_Amount 10000.0 Available_Cash 123456.78

Error 1: Operation not allowed. Operator/operand type mismatch.
(Referring to if(StaticVarGet("Trade_Amount"

I am curious why I am getting the type mismatch error and if there are any 
ideas for a workaround.

Thanks in advance