When I first started with digital modes fldigi didn't decode the way I expected it.
The problem was the radio output level was simply too high.
Digital modes are all about signal to noise ratios and not absolute signal levels
Screenshots on this page are intended to illustrate what signal level is required for fldigi to provide successful decoding.
This is a typical waterfall display on 14.070MHz. Take particular note of the background which has only a few background noise specs showing in yellow.
Adjust the radio output level and noise blanker until your
The following image shows PSK signals which are too weak for reliable decoding:
Here is a PSK signal which should decode almost perfectly: