Monodevelop C# script execution bug

I have a very simple if statement that is not working as expected.

My main problem is, that the immediate window evaluates the if statement differently then the code execution:

   if( FreeProductStorageVolume < product.Volume * quantity )
   {
      Debug.Log( FreeProductStorageVolume );
      Debug.Log( product.Volume );
      Debug.Log( quantity );
      Debug.Log( product.Volume * quantity );
      canProduce = false;
   }

all the variables are floats

everything suggests that the breakpoint in line 824 should not be hit.

even the Immediate window evaluates the if() statement as false.

has anything like this happened to anyone else?