How do I show the following label for our sewer pipes?

Facility ID

Pipe Length rounded off to the tenth

This is the script I attempted to use to show this: 

'<BOL>' + [GXP_IDNEW] + '</BOL>' + '\n' + [Shape_Length] + round(float([Shape_Length]), 1) + "'" + ", " + [PIPE_DIA]

I keep getting the following error when writing the script

Invalid Expression

Error 0 on line 0.

Traceback (most recent call last):

  File "<expression>", Line 1, in <module>

  File "<string>", line 2, in esri_FindLabel

TypeError: must be str, not float.

Basically, when I show JUST the pipe length rounded off to the tenth, it will display. But, when I include it in a stacked label, the error shows up.

What am I doing wrong?