GE gas turbine tripped due to loss of flame after purge complete during startup. It has been observe that moisture and water found in the flame detector every time it tripped. After cleaning the water content from flame detector, the unit then detect firing and sustain. But every time after unit started this loss of flame tripping is occurs. After purge complete GCV and SRV also opening, and FSR also shows 20% but firing restricted as flame detector couldn't detect flame due to moisture deposited on the surface, and every time it need to be cleaned. The unit control system is Make-VIe. What might be the cause of water and moisture on the surface of flame detector?