EA buy at ibands mode-lower and sell at ibands mode upper

[Hossein Zandi]

hello,

I'm trying to write an expert that buys at lower band of the Bollinger bands and sell at upper bands and this is my code \

Ask<=(iBands(Symbol(),PERIOD_CURRENT,0,20,2,0,MODE_LOWER,1)

Bid>=iBands(Symbol(),PERIOD_CURRENT,0,20,2,0,MODE_UPPER,1)

but the EA only opens sell positions and not any buy positions can anyone help me?