Chinook RV

I'm looking at the dipstick for the hydraulic fluid. No fluid is visible, but one of my slide outs is stuck open for the moment. My understanding is that the reservoir level is best checked with the slideouts retracted. Anyone have any wisdom to impart?? I'm wondering at this point if thats the root of my problem!

Likely that's the problem. I would fill it to the dipstick level try it. If it works, open a d close it a bit and recheck the fluid level.