why this Function--viVSPrintf doesn't work in VB6.0?

[天涯]

Dear Expert:

  I'm a newer of VB,now my problem is:

  I use VISA32-DLL,when I run:

   For i=0 to 50

   Call viVSPrintf(vi, Temp, "FREQ:CENT %dMHz", (925 + i * 0.2))  -------------Temp As String;vi As long
   Call ibwrt(ComHandler, Temp) 

  I can't get the Temp value,so I can't write the string to control the R&S FSQ,

  How to config the parameters of this function:viVSPrintf?why I can't get the String?

[天涯]

Instead My purpose is writing a expression into a String because GPIB command ibwrt() can't support a String with variable,

and I'm not sure if the parameters i wrote is right?

i will appreciate any information from you,thanks