markup dynamics wrong size

[Eric Flesher]

Wondering if anyone has experienced the following problem:

When creating new centered dynamics in a piano staff in ver. 2.11.55  
(and several earlier versions) using \markup, three things happen:

1. the markup text created is significantly larger than the normal  
dynamic size
2. the text does not align with other dynamic markings
3. the presence of the markup text forces additional space between  
the staves

The dynamic marking concerned is contained in a variable thus:
pocoF = \markup  { \italic poco \dynamic f }


and is deployed locally as follows:
\times 4/5 { s16 s\mp s s-\pocoF s\> } \times 4/5 { s8\! s\mp s16 } s4

(I would include more code, but the file is extremely long.)

Any idea what might be wrong here, and how this could be fixed?

Thanks,
EF