I just added a Basimilus Iteritas Alter to my rack. I including it in a patch and the lights on all my modules started flashing, at the same time.
Is this a warning sign?.
My rack is a Behringer Go, it's got 3 x 1 amp sections, of which none are overloaded.

I hope you switched off straight away!!!

are you sure the power cable is in the right way? on both the module and the busboard

are you sure the power cable is correctly made - red stripe should be to left when looking at the keyed side on both connectors - lining up with a tiny embossed triangle

have you left 30%ish overhead on each of those sections on the +ve rail?

it could be over draw on one of the other rails? -ve perhaps or 5v - same for headroom! I'd be surprised if it were 5v though, -ve not so much - I have a mantis, which b-company 'cloned' the go case power from, and I think that is under-powered on the -ve rail (but I have quite a few -ve hungry video modules in there)

if all that is ok - ie the connection is good and there is (supposedly) ample headrooom on all rails - then there's still the possibility of inrush being the cause - and not necessarily just from this module - it is cumulative - it's quite likely that if you have multiple modules with higher inrush draw than stated (often digital modules) that this can occur - so spread the digital modules out as much as possible - and if necessary shift them around a few times until it works - try moving things around so that this module is powered from another section - or remove some modules from that section and move them to another that has more room

if you still have problems - either add an additional power supply rack wart module style (ugly hp thieves that they are) - or wmd make a plug in for the power connector that delays the start up of a module for a short time to delay the inrush until other modules have started up

maybe creating an abstract version of your rack here would be a good idea - use 3 rows instead of 2 - each row is a section of the power supply - if you go to the bottom of the list view you can then see consumption by row (or in this case section of power supply) - I often do this where I have 2 power supplies for 3 rows in a diy case - if you make the rack public and copy paste the url in here maybe someone will take a look and help you

Utility modules are the inexpensive, dull polish that makes the expensive, shiny modules actually shine!!!

Thank you so much for taking the time to give me advice.
I've moved a few modules around and it does seem to be OK now.
I will do a 3 row rack and post here, to double check.
Thanks again.

and yeah, it was switched off pronto.